Microformats Wiki - User contributions [en]

h-event

2017-02-22T09:17:35Z

Andy sky: /* Properties */ format fix

<entry-title>h-event</entry-title>
[[User:Tantek|Tantek Çelik]] (Editor)
----
<dfn style="font-style:normal;font-weight:bold">h-event</dfn> is a simple, open format for publishing events on the web. h-event is one of several open [[microformats|microformat]] draft standards suitable for embedding data in HTML/HTML5.

h-event is the [[microformats2]] update to [[hCalendar]].

{{cc0-owfa-license}}

== Example ==
Here is a simple event example:

<source lang=html4strict>
<div class="h-event">
<h1 class="p-name">Microformats Meetup</h1>
From
<time class="dt-start" datetime="2013-06-30 12:00">30th June 2013, 12:00</time>
to <time class="dt-end" datetime="2013-06-30 18:00">18:00</time>
at Some bar in SF
Get together and discuss all things microformats-related.
</div>
</source>

Parsed JSON:
<source lang=javascript>
{
"items": [
{
"type": [
"h-event"
],
"properties": {
"name": [
"Microformats Meetup"
],
"start": [
"2013-06-30 12:00:00"
],
"end": [
"2013-06-30 18:00:00"
],
"location": [
"Some bar in SF"
],
"summary": [
"Get together and discuss all things microformats-related."
]
}
}
]
}
</source>

=== Get started ===
The class '''<code>h-event</code>''' is a ''root class name'' that indicates the presence of an h-event.

'''p-name''', '''dt-start''', '''dt-end''', '''p-location''', '''p-summary''', and the other h-event property class names listed below define ''properties'' of the h-event.

See [[microformats2-parsing]] to learn more about property class names.

== Properties ==
h-event properties, inside an element with class '''h-event''':
* '''<code>p-name</code>''' - event name (or title)
* '''<code>p-summary</code>''' - short summary of the event
* '''<code>dt-start</code>''' - datetime the event starts
* '''<code>dt-end</code>''' - datetime the event ends
* '''<code>dt-duration</code>''' - duration of the event
* '''<code>p-description</code>''' - more detailed description of the event
* '''<code>u-url</code>''' - permalink for the event
* '''<code>p-category</code>''' - event category(ies)/tag(s)
* '''<code>p-location</code>''' - where the event takes place, optionally embedded [[h-card]], [[h-adr]], or [[h-geo]]
Experimental properties currently in use in the wild but not (yet) part of the official h-entry spec:
* '''<code>p-attendee</code>''' - a person attending the event, optionally embed [[h-card]]
<div class="discussion">
* This draft has not been updated in almost 2 years. During this period, <code>h-entry</code> <code>p-rsvp</code> has been standardised, thus making it robust and mature enough for the addition. I guess it's about time to unlabel <code>p-attendee</code> as experimental.
* I would also suggest to extend expected value to [[h-entry]], so that, while the personal info can be preserved, the attendee can also support p-rsvp property of h-entry.
</div>

All properties are optional.

== Status ==
'''h-event''' is a microformats.org draft specification. Public discussion on h-event takes place on [[h-event-feedback]] and the #microformats [[irc]] channel on irc.freenode.net.

h-event is ready to use and implemented in the wild, but for backwards compatibility you should also mark h-events up as classic [[hCalendar]] events.

== Property Details ==
(stub, to be expanded)

=== p-location ===
<code>p-location</code> is typically a physical address, optionally marked up with [[h-adr]], for example:

<source lang=html4strict>

17 Austerstræti
Reykjavík
Iceland

</source>

=== Reserved Properties ===
Reserved properties:
* '''<code>p-organizer</code>''' - a person (co-)organizing the event, optionally embed [[h-card]] {{main|h-card}}
** proposed as way to [https://github.com/snarfed/bridgy/issues/275 implement copying an event organizer to Eventbrite]

== Examples in the wild ==
Real world in the wild examples:

* ... add uses of h-event you see in the wild here.
* [http://www.w3.org/conf/ W3Conf 2013] uses h-event for the main event, and h-card for all the speakers and notable attendees. The h-cards make particularly good use of implied name, url, and photo properties.
* [http://tantek.com/ Tantek Çelik] uses h-event on his home page
* [http://tantek.com/presentations/2012/06/microformats microformats.org at 7 years] presentation with h-event
* [http://tantek.com/presentations/2012/06/pdf2012-indieweb.html Rise of the Indie Web hCards] (from Personal Democracy Forum 2012 #pdf12 #pdf2012) has [[microformats2]] h-event and h-card markup
* WebMaker by Mozilla has h-event and h-card on event search (e.g. [https://webmaker.org/en-US/events/near/?lat=45.5234515&lng=-122.6762071 search near Portland Oregon]) and event pages (e.g. [https://webmaker.org/en-US/events/192f56eb9/ IndieWebCamp 2012]).[https://twitter.com/microformats/status/212207925643587585]
* [http://indiewebcamp.com IndieWebCamp] has [[microformats2]] h-event markup with embedded h-cards for the organizers and the location.
* [https://wiki.mozilla.org/Events Mozilla Events] page has [[microformats2]] h-event markup with attendees marked up with h-card.

See [[microformats2#Examples_in_the_wild|microformats2 examples in the wild]] for more

== Validating ==
{{h-spec-section-validating}}

== Backward Compatibility ==
=== Publisher Compatibility ===
For backward compatibility, you may wish to use classic [[hCalendar]] classnames in addition to the more future-proof h-event properties, for example:

<source lang=html4strict>
<div class="h-event vevent">
<h1 class="p-name summary">Some great event</h1>
</div>
</div>
</source>

=== Parser Compatibility ===
Microformats parsers {{should}} detect classic properties only if a classic root class name is found and parse them as microformats2 properties.

If an "h-event" is found, don't look for a "vevent" on the same element.

Compat root class name: <code id="vevent">vevent</code> 
Properties: (parsed as '''p-''' plain text unless otherwise specified)
* <code>summary</code> - parse as '''<code>p-name</code>'''
* <code>dtstart</code> - parse as '''<code>dt-start</code>'''
* <code>dtend</code> - parse as '''<code>dt-end</code>'''
* <code>duration</code> - parse as '''<code>dt-duration</code>'''
* <code>description</code>
* <code>url</code> - parse as '''u-'''
* <code>category</code>
* <code>location</code> - including compat root <code>vcard</code> in the absence of <code>h-card</code>, and compat root <code>adr</code> in the absence of <code>h-adr</code>
* <code>geo</code> - parse as '''<code>p-location h-geo</code>''' including compat root <code>geo</code>

=== iCalendar Compatibility ===
hCalendar-specific implementations that perform custom display or translation to iCalendar .ics {{should}} prefer <code>p-name</code> over <code>p-summary</code>, and use <code>p-summary</code> value(s) as a fallback if there is no <code>p-name</code>.

== Background ==
This work is based on the existing [[hCalendar]] and [[iCalendar]] specifications.

== Design Principles ==
(stub, expand)

== See Also ==
* [[h-calendar-to-do]]
* [[microformats2]]
* [[microformats2-parsing]]
* [[h-adr]]
* [[h-geo]]
* [[h-card]]
* [[hCalendar]]

[[Category:Draft Specifications]]

h-event

2017-02-22T09:17:12Z

Andy sky: /* Properties */ extend p-attendee to h-entry

<entry-title>h-event</entry-title>
[[User:Tantek|Tantek Çelik]] (Editor)
----
<dfn style="font-style:normal;font-weight:bold">h-event</dfn> is a simple, open format for publishing events on the web. h-event is one of several open [[microformats|microformat]] draft standards suitable for embedding data in HTML/HTML5.

h-event is the [[microformats2]] update to [[hCalendar]].

{{cc0-owfa-license}}

== Example ==
Here is a simple event example:

<source lang=html4strict>
<div class="h-event">
<h1 class="p-name">Microformats Meetup</h1>
From
<time class="dt-start" datetime="2013-06-30 12:00">30th June 2013, 12:00</time>
to <time class="dt-end" datetime="2013-06-30 18:00">18:00</time>
at Some bar in SF
Get together and discuss all things microformats-related.
</div>
</source>

Parsed JSON:
<source lang=javascript>
{
"items": [
{
"type": [
"h-event"
],
"properties": {
"name": [
"Microformats Meetup"
],
"start": [
"2013-06-30 12:00:00"
],
"end": [
"2013-06-30 18:00:00"
],
"location": [
"Some bar in SF"
],
"summary": [
"Get together and discuss all things microformats-related."
]
}
}
]
}
</source>

=== Get started ===
The class '''<code>h-event</code>''' is a ''root class name'' that indicates the presence of an h-event.

'''p-name''', '''dt-start''', '''dt-end''', '''p-location''', '''p-summary''', and the other h-event property class names listed below define ''properties'' of the h-event.

See [[microformats2-parsing]] to learn more about property class names.

== Properties ==
h-event properties, inside an element with class '''h-event''':
* '''<code>p-name</code>''' - event name (or title)
* '''<code>p-summary</code>''' - short summary of the event
* '''<code>dt-start</code>''' - datetime the event starts
* '''<code>dt-end</code>''' - datetime the event ends
* '''<code>dt-duration</code>''' - duration of the event
* '''<code>p-description</code>''' - more detailed description of the event
* '''<code>u-url</code>''' - permalink for the event
* '''<code>p-category</code>''' - event category(ies)/tag(s)
* '''<code>p-location</code>''' - where the event takes place, optionally embedded [[h-card]], [[h-adr]], or [[h-geo]]
Experimental properties currently in use in the wild but not (yet) part of the official h-entry spec:
* '''<code>p-attendee</code>''' - a person attending the event, optionally embed [[h-card]]
<div class="discussion">
* This draft has not been updated in almost 2 years. During this period, <code>h-entry</code> <code>p-rsvp</code> has been standardised, thus making it robust and mature enough for the addition. I guess it's about time to unlabel <code>p-attendee</code> as experimental.
I would also suggest to extend expected value to [[h-entry]], so that, while the personal info can be preserved, the attendee can also support p-rsvp property of h-entry.
</div>

All properties are optional.

== Status ==
'''h-event''' is a microformats.org draft specification. Public discussion on h-event takes place on [[h-event-feedback]] and the #microformats [[irc]] channel on irc.freenode.net.

h-event is ready to use and implemented in the wild, but for backwards compatibility you should also mark h-events up as classic [[hCalendar]] events.

== Property Details ==
(stub, to be expanded)

=== p-location ===
<code>p-location</code> is typically a physical address, optionally marked up with [[h-adr]], for example:

<source lang=html4strict>

17 Austerstræti
Reykjavík
Iceland

</source>

=== Reserved Properties ===
Reserved properties:
* '''<code>p-organizer</code>''' - a person (co-)organizing the event, optionally embed [[h-card]] {{main|h-card}}
** proposed as way to [https://github.com/snarfed/bridgy/issues/275 implement copying an event organizer to Eventbrite]

== Examples in the wild ==
Real world in the wild examples:

* ... add uses of h-event you see in the wild here.
* [http://www.w3.org/conf/ W3Conf 2013] uses h-event for the main event, and h-card for all the speakers and notable attendees. The h-cards make particularly good use of implied name, url, and photo properties.
* [http://tantek.com/ Tantek Çelik] uses h-event on his home page
* [http://tantek.com/presentations/2012/06/microformats microformats.org at 7 years] presentation with h-event
* [http://tantek.com/presentations/2012/06/pdf2012-indieweb.html Rise of the Indie Web hCards] (from Personal Democracy Forum 2012 #pdf12 #pdf2012) has [[microformats2]] h-event and h-card markup
* WebMaker by Mozilla has h-event and h-card on event search (e.g. [https://webmaker.org/en-US/events/near/?lat=45.5234515&lng=-122.6762071 search near Portland Oregon]) and event pages (e.g. [https://webmaker.org/en-US/events/192f56eb9/ IndieWebCamp 2012]).[https://twitter.com/microformats/status/212207925643587585]
* [http://indiewebcamp.com IndieWebCamp] has [[microformats2]] h-event markup with embedded h-cards for the organizers and the location.
* [https://wiki.mozilla.org/Events Mozilla Events] page has [[microformats2]] h-event markup with attendees marked up with h-card.

See [[microformats2#Examples_in_the_wild|microformats2 examples in the wild]] for more

== Validating ==
{{h-spec-section-validating}}

== Backward Compatibility ==
=== Publisher Compatibility ===
For backward compatibility, you may wish to use classic [[hCalendar]] classnames in addition to the more future-proof h-event properties, for example:

<source lang=html4strict>
<div class="h-event vevent">
<h1 class="p-name summary">Some great event</h1>
</div>
</div>
</source>

=== Parser Compatibility ===
Microformats parsers {{should}} detect classic properties only if a classic root class name is found and parse them as microformats2 properties.

If an "h-event" is found, don't look for a "vevent" on the same element.

Compat root class name: <code id="vevent">vevent</code> 
Properties: (parsed as '''p-''' plain text unless otherwise specified)
* <code>summary</code> - parse as '''<code>p-name</code>'''
* <code>dtstart</code> - parse as '''<code>dt-start</code>'''
* <code>dtend</code> - parse as '''<code>dt-end</code>'''
* <code>duration</code> - parse as '''<code>dt-duration</code>'''
* <code>description</code>
* <code>url</code> - parse as '''u-'''
* <code>category</code>
* <code>location</code> - including compat root <code>vcard</code> in the absence of <code>h-card</code>, and compat root <code>adr</code> in the absence of <code>h-adr</code>
* <code>geo</code> - parse as '''<code>p-location h-geo</code>''' including compat root <code>geo</code>

=== iCalendar Compatibility ===
hCalendar-specific implementations that perform custom display or translation to iCalendar .ics {{should}} prefer <code>p-name</code> over <code>p-summary</code>, and use <code>p-summary</code> value(s) as a fallback if there is no <code>p-name</code>.

== Background ==
This work is based on the existing [[hCalendar]] and [[iCalendar]] specifications.

== Design Principles ==
(stub, expand)

== See Also ==
* [[h-calendar-to-do]]
* [[microformats2]]
* [[microformats2-parsing]]
* [[h-adr]]
* [[h-geo]]
* [[h-card]]
* [[hCalendar]]

[[Category:Draft Specifications]]

h-event

2017-02-21T13:29:00Z

Andy sky: /* Properties */ p-attendee

<entry-title>h-event</entry-title>
[[User:Tantek|Tantek Çelik]] (Editor)
----
<dfn style="font-style:normal;font-weight:bold">h-event</dfn> is a simple, open format for publishing events on the web. h-event is one of several open [[microformats|microformat]] draft standards suitable for embedding data in HTML/HTML5.

h-event is the [[microformats2]] update to [[hCalendar]].

{{cc0-owfa-license}}

== Example ==
Here is a simple event example:

<source lang=html4strict>
<div class="h-event">
<h1 class="p-name">Microformats Meetup</h1>
From
<time class="dt-start" datetime="2013-06-30 12:00">30th June 2013, 12:00</time>
to <time class="dt-end" datetime="2013-06-30 18:00">18:00</time>
at Some bar in SF
Get together and discuss all things microformats-related.
</div>
</source>

Parsed JSON:
<source lang=javascript>
{
"items": [
{
"type": [
"h-event"
],
"properties": {
"name": [
"Microformats Meetup"
],
"start": [
"2013-06-30 12:00:00"
],
"end": [
"2013-06-30 18:00:00"
],
"location": [
"Some bar in SF"
],
"summary": [
"Get together and discuss all things microformats-related."
]
}
}
]
}
</source>

=== Get started ===
The class '''<code>h-event</code>''' is a ''root class name'' that indicates the presence of an h-event.

'''p-name''', '''dt-start''', '''dt-end''', '''p-location''', '''p-summary''', and the other h-event property class names listed below define ''properties'' of the h-event.

See [[microformats2-parsing]] to learn more about property class names.

== Properties ==
h-event properties, inside an element with class '''h-event''':
* '''<code>p-name</code>''' - event name (or title)
* '''<code>p-summary</code>''' - short summary of the event
* '''<code>dt-start</code>''' - datetime the event starts
* '''<code>dt-end</code>''' - datetime the event ends
* '''<code>dt-duration</code>''' - duration of the event
* '''<code>p-description</code>''' - more detailed description of the event
* '''<code>u-url</code>''' - permalink for the event
* '''<code>p-category</code>''' - event category(ies)/tag(s)
* '''<code>p-location</code>''' - where the event takes place, optionally embedded [[h-card]], [[h-adr]], or [[h-geo]]
Experimental properties currently in use in the wild but not (yet) part of the official h-entry spec:
* '''<code>p-attendee</code>''' - a person attending the event, optionally embed [[h-card]]
<div class="discussion">
* This draft has not been updated in almost 2 years. During this period other sites have referenced the <code>p-attendee</code> property (e.g. [https://indieweb.org/event IndieWebCamp event]). In addition to this, <code>h-entry</code> <code>p-rsvp</code> has been standardised, thus making it robust and mature enough for the addition. I guess it's about time to unlabel <code>p-attendee</code> as experimental.
</div>

All properties are optional.

== Status ==
'''h-event''' is a microformats.org draft specification. Public discussion on h-event takes place on [[h-event-feedback]] and the #microformats [[irc]] channel on irc.freenode.net.

h-event is ready to use and implemented in the wild, but for backwards compatibility you should also mark h-events up as classic [[hCalendar]] events.

== Property Details ==
(stub, to be expanded)

=== p-location ===
<code>p-location</code> is typically a physical address, optionally marked up with [[h-adr]], for example:

<source lang=html4strict>

17 Austerstræti
Reykjavík
Iceland

</source>

=== Reserved Properties ===
Reserved properties:
* '''<code>p-organizer</code>''' - a person (co-)organizing the event, optionally embed [[h-card]] {{main|h-card}}
** proposed as way to [https://github.com/snarfed/bridgy/issues/275 implement copying an event organizer to Eventbrite]

== Examples in the wild ==
Real world in the wild examples:

* ... add uses of h-event you see in the wild here.
* [http://www.w3.org/conf/ W3Conf 2013] uses h-event for the main event, and h-card for all the speakers and notable attendees. The h-cards make particularly good use of implied name, url, and photo properties.
* [http://tantek.com/ Tantek Çelik] uses h-event on his home page
* [http://tantek.com/presentations/2012/06/microformats microformats.org at 7 years] presentation with h-event
* [http://tantek.com/presentations/2012/06/pdf2012-indieweb.html Rise of the Indie Web hCards] (from Personal Democracy Forum 2012 #pdf12 #pdf2012) has [[microformats2]] h-event and h-card markup
* WebMaker by Mozilla has h-event and h-card on event search (e.g. [https://webmaker.org/en-US/events/near/?lat=45.5234515&lng=-122.6762071 search near Portland Oregon]) and event pages (e.g. [https://webmaker.org/en-US/events/192f56eb9/ IndieWebCamp 2012]).[https://twitter.com/microformats/status/212207925643587585]
* [http://indiewebcamp.com IndieWebCamp] has [[microformats2]] h-event markup with embedded h-cards for the organizers and the location.
* [https://wiki.mozilla.org/Events Mozilla Events] page has [[microformats2]] h-event markup with attendees marked up with h-card.

See [[microformats2#Examples_in_the_wild|microformats2 examples in the wild]] for more

== Validating ==
{{h-spec-section-validating}}

== Backward Compatibility ==
=== Publisher Compatibility ===
For backward compatibility, you may wish to use classic [[hCalendar]] classnames in addition to the more future-proof h-event properties, for example:

<source lang=html4strict>
<div class="h-event vevent">
<h1 class="p-name summary">Some great event</h1>
</div>
</div>
</source>

=== Parser Compatibility ===
Microformats parsers {{should}} detect classic properties only if a classic root class name is found and parse them as microformats2 properties.

If an "h-event" is found, don't look for a "vevent" on the same element.

Compat root class name: <code id="vevent">vevent</code> 
Properties: (parsed as '''p-''' plain text unless otherwise specified)
* <code>summary</code> - parse as '''<code>p-name</code>'''
* <code>dtstart</code> - parse as '''<code>dt-start</code>'''
* <code>dtend</code> - parse as '''<code>dt-end</code>'''
* <code>duration</code> - parse as '''<code>dt-duration</code>'''
* <code>description</code>
* <code>url</code> - parse as '''u-'''
* <code>category</code>
* <code>location</code> - including compat root <code>vcard</code> in the absence of <code>h-card</code>, and compat root <code>adr</code> in the absence of <code>h-adr</code>
* <code>geo</code> - parse as '''<code>p-location h-geo</code>''' including compat root <code>geo</code>

=== iCalendar Compatibility ===
hCalendar-specific implementations that perform custom display or translation to iCalendar .ics {{should}} prefer <code>p-name</code> over <code>p-summary</code>, and use <code>p-summary</code> value(s) as a fallback if there is no <code>p-name</code>.

== Background ==
This work is based on the existing [[hCalendar]] and [[iCalendar]] specifications.

== Design Principles ==
(stub, expand)

== See Also ==
* [[h-calendar-to-do]]
* [[microformats2]]
* [[microformats2-parsing]]
* [[h-adr]]
* [[h-geo]]
* [[h-card]]
* [[hCalendar]]

[[Category:Draft Specifications]]

microformats2-prefixes

2017-01-30T00:27:54Z

Andy sky: /* COMPATIBILITY */ typo

<entry-title>microformats 2 prefix conventions</entry-title>

[[microformats 2]] uses a small number of prefixes to distinguish microformats 2 class names from other class names.

== motivating causes ==
As described on the [[microformats 2]] page.

=== distinguishing properties from other classes ===
Current microformats properties re-use generic terms like "summary", "photo", "updated" both for ease of use and understanding.

However, through longer term experience, we've seen sites that accidentally drop (or break) their microformats support (e.g. Upcoming.org, Facebook) because web authors sometimes rewrite all their class names, and either are unaware that microformats were in the page, or couldn't easily distinguish microformats property class names from other site-specific class names.

This issue has been reported by a number of web authors:
* [http://html5doctor.com/microformats/#comment-10241 Wim's comment on HTML5Doctor] "Authors use classes like 'url' or 'region' all the time ... All sorts of markup might look like a microformat."
* ...

There has also been an anecdotal report of a design firm who was not (yet) familiar with microformats seeing the "extra" classes that "that don't seem to be used" (without corresponding CSS rules) and asking if they "can remove them". By making microformats class names different from generic words, authors unfamiliar with microformats may at least notice such distinction and infer special functionality accordingly.

Thus microformats 2 uses ''prefixes'' for property class names, e.g.:
* '''p-summary''' instead of ''summary''
* '''u-photo''' instead of ''photo''
* '''dt-updated''' instead of ''updated''

Such prefixing of all microformats class names was first suggested by Scott Isaacs of Microsoft to Tantek on a visit to Microsoft sometime in 2006/2007, but specifically aimed at making microformats easier to parse. At the time the suggestion was rejected since microformats were focused on web authors rather than parsers.

However, since experience has shown that distinguishing property class names is an issue for '''both web authors and parser developers''', this is a key change that microformats 2 is adopting. See the next section for details.

=== existing microformats parsing requirements ===
A non-trivial number of parser and tools developers have been sufficiently frustrated with some general issues with microformats that they've done the significant extra work to support very different and less friendly alternatives (microdata, RDFa). Based on this real-world data (market behavior), it behooves us to address these general issues with microformats for this constituency.

COMMUNITY and TOOLS (that) USE MICROFORMATS
* parser / parsing
* structured
* getting the data out
* json - 1:1 mapping

[[parsing]] microformats currently requires
# a list of root class names of each microformat to be parsed
# a list of properties for each specific microformats, along with knowledge of the type of each property in order to parse their data from potentially different portions of the HTML markup
# some number of format-specific specific rules (markup/content optimizations)

This has meant that whenever a new microformat is drafted/specificied/adopted, parsers need to updated to handle it correctly, at a minimum to parse them when inside other microformats and avoid errantly implying properties from one to the other (containment, [[mfo]] problem).

== microformats 2 prefixes ==
=== naming conventions for generic parsing ===
There is a fairly simple solution to #1 and #2 from the above list, and we can make progress towards minimizing #3. In short:

'''Proposal: a set of naming conventions for microformat root class names and properties that make it obvious when:'''
* a class name represents a microformat root class name
* a class name represents a microformat property name
* a class name represents a microformat property that needs special parsing (specific type of property).

In particular - derived from the real world examples of existing proven microformats (rather than any abstraction of what a schema should have)
* '''"h-*" for root class names''', e.g. "h-card", "h-event", "h-entry"
** The 'h-' prefix is based on the existing microformats naming pattern of starting with 'h'.
* '''"p-*" for simple (text) properties''', e.g. "p-fn", "p-summary"
** vocabulary generic parsing, element text in general, treat certain HTML element/attribute combination as special and use those first, e.g. img/alt, abbr/title.
** The 'p-' prefix is based on the word "property" starting with 'p'.
* '''"u-*" for URL properties''', e.g. "u-url", "u-photo", "u-logo"
** special parsing required: prefer a/href, img/src, object/data etc. attributes to element contents.
** The 'u-' prefix is based on URL/URI starting with the letter 'u', which is the type of most of these related properties.
* '''"dt-*" for datetime properties''', e.g. "dt-start", "dt-end", "dt-bday"
** special parsing required: [[value-class-pattern]], in particular separate date time value parsing for better human readabillity / DRY balance.
** The 'dt-' prefix is based on "date time" having the initials "dt" and the preponderance of existing date time properties starting with "dt", e.g. dtstart, dtend, dtstamp, dtreviewed.
*** Initially I had proposed "dt-*" but Chris Messina suggested reducing it to "d-*" so that all prefixes were a single letter - made sense.
*** However, I've noticed that Google+ is using "d-*" class names on [https://plus.google.com/109182513536739786206 profile pages], thus we can't really use 'd-' as a microformats 2 property parsing prefix. [[User:Tantek|Tantek]] 03:00, 22 July 2011 (UTC)
* '''"e-*" for element tree properties''' where the entire contained element hierarchy is the value, e.g. "e-content" (formerly "entry-content") for [[hAtom]]. The 'e-' prefix can also be mnemonically remembered as "element tree", "embedded markup", or "encapsulated markup".
** special parsing required: follow the [http://www.whatwg.org/specs/web-apps/current-work/multipage/the-end.html#serializing-html-fragments HTML spec: Serializing HTML Fragments algorithm] to create a serialization.

This provides a simpler transition/education story for existing microformats authors/publishers:
* "h*" to "h-*", "dt*" to "dt-*", url-like properties to "u-*", entire embedded markup to "e-*", and "p-*" for all "plain text" properties.

==== prefixes for future consideration ====
possibly also:
<div class="discussion">
* '''"s-*" for structured properties''' basically s-* works just like h-* except that no properties (e.g. 'name','url','photo') are implied when there are no properties present. Example uses: s-geo and s-adr. This is being considered as a result of [[microformats-2-parsing#Parsing_Literal_Values|microformats 2 parsing discussions]]. We can try it and see what happens. There's also no harm if publishers just use "h-" structures, they just (possibly) get a few extra properties if they happen to omit properties.
** -1. Although I do think the implied-literal parsing behaviour carries some complications and parsed-cruft with more 'structural' formats, introducing a further generic prefix to differentiate one kind of format from another is oesoteric, won't be understood by authors (we're already considering a full reversal rename of 'fn' to 'name' in response to user comprehension), and we've seen historically that mixed prefixes (v and h) also cause muddle. --[[User:BenWard|BenWard]] 06:30, 5 October 2011 (UTC)
*** This is good reasoning, especially the comparison to v vs. h prefixed root class names (my experience with authors concurs with that). Each new prefix introduces complexity and thus must have advantages sufficient to exceed the complexity cost. [[User:Tantek|Tantek]] 06:55, 5 October 2011 (UTC)
** Furthermore, both of the examples given here have in-the-wild use cases for literal parsing: Geo's existing documented optimisation of <code>1.233;0.453</code> is applied in two (one valid) manners with the <code>abbr</code> element (incorrectly as an expansion of a place name, and as an alternative to degree-format co-ordinates. Coordinates are also displayed in-place alongside map references, markers, and the like.) In the case of <code>adr</code>, there's an overlap with existing uses of the <code>label</code> label property, which is used in cases of unstructured addresses (common in most social network profile systems, also in vcalendar.) Based on previous discussion around unstructured addresses, Twitter uses <code><* class="adr"><* class="label"></code> on profiles ([https://twitter.com/intent/user?screen_name=benward&detailed Example].) Having literal parsing of <code>adr</code> would be neater though, if <code>label</code> were to be deprecated. --[[User:BenWard|BenWard]] 06:30, 5 October 2011 (UTC)
*** [[geo]] has been historically quite problematic in practice, despite our efforts at making it work better via optimizations. I'd like to see real world examples of "Coordinates are also displayed in-place alongside map references, markers, and the like" documented on a page like [[geo-examples]] so we can see how any kind of geo-markup could/would help. Interesting about the Twitter use of 'label' inside 'adr' - quite prescient as [[vCard4]] moved 'label' from being its own top-level property to being an attribute (what we used to call subproperty) of 'adr'. Thus we should consider adding 'p-label' as a property for 'h-adr', given a) Twitter's real world usage, b) the refactoring of label into adr in vCard4. [[User:Tantek|Tantek]] 06:55, 5 October 2011 (UTC)
* '''"e-*" for properties''' where the entire contained element hierarchy is the value, e.g. "e-content" (formerly "entry-content") for [[hAtom]]. (2011-09-21 note: this has now been included in microformats 2, the below discussion is kept for posterity [[User:Tantek|Tantek]] 09:44, 21 September 2011 (UTC))
** unclear if this is necessary in general. and if so, if this is only for hAtom, that's insufficient to justify putting it in the generic syntax.
** Would be sufficient to have all <code>p-</code> properties parse the complete content, including any nested mark-up if present, and then implementations to sanitize/run a <code>strip_tags</code> style function (as per data input best practice) as appropriate. --[[User:BenWard|BenWard]] 22:05, 19 September 2011 (UTC)
** Ouch that sounds like passing on complexity downstream for all cases just to handle *one* known use-case so far. Since we'd typically do the opposite (simplify for the 99% case over the 1% case), passing on content including mark-up by default seems like a step backwards. Also, given how many vulnerabilities seem to deal with parsing/filtering, doing that *first* rather than burdening downstream implementations seems like the right choice. I'd rather wait til we get a concrete complaint from a microformats-2 hAtom consumer before worrying about this for hAtom 2.0. Or are there other current real world use cases besides Atom? [[User:Tantek|Tantek]] 22:22, 19 September 2011 (UTC)
*** In addition to <code>entry-content</code> in hAtom there's also <code>entry-summary</code>, plus any large region of text in other microformats, which at the very least can commonly contain additional hyperlinks, images, and phrasing mark-up: <code>description</code> in hCal, hReview, hProduct, hListing, <code>note</code> in hCard, <code>ingredient</code>, <code>instructions</code> in hRecipe may link to a store, or wikipedia entry for the ingredient, or include an image to illustrate a step of a recipe, as well as recipe instructions that are expressed as lists. If an author/publisher marks up a property in such a way that it contains further mark-up, that mark-up should be assumed to be part of the value. It's always going to be up to an implementation to decide whether it wishes to translate that HTML mark-up into some other format (e.g. Markdown-esque text annotation when converting to something like <code>vcard</code>, or some other kind of formatting language on non-HTML platforms, or stripping text altogether. —[[User:BenWard|BenWard]] 01:05, 20 September 2011 (UTC)
**** While hAtom's <code>entry-content</code> and possibly hCard's <code>note</code> may be the only existing practical use-cases (<code>entry-summary</code> and other "large region of text" are potential/prospective use cases), I'm now convinced the hAtom use-case alone is worthy of including the "e-" prefix because it enables a full fidelity replacement for typical Atom use cases. [[User:Tantek|Tantek]] 09:44, 21 September 2011 (UTC)
* '''"i-*" for ID properties''', e.g. "i-uid" (if this is the only one, then perhaps we just always re-use "uid" or collapse with "u-*" into "u-id".)
** parsing is no different than "u-*" parsing, thus no need to introduce for now.
* '''"n-*" for numbers''', e.g. "n-rating", "n-geo", where the numbers may have different human-readable-friendly and decimal/machine values (e.g. with geo lat/long degrees minutes seconds vs decimal).
** requires definition of how would different parsing work before worthy of consideration.
* '''"t-*" for time duration''', e.g. "t-duration" in [[hCalendar]], [[hAudio]], [[hRecipe]] (note also Google's hRecipe extensions "preptime", "cooktime", "totaltime")
** requires definition of how would different parsing work before worthy of consideration.
** now that the HTML5 <time> element supports representing durations, we should simply incorporate duration (and timezone at that) into the 'dt-' datetime parsing rules. Certainly no need for a separate prefix. [[User:Tantek|Tantek]] 08:45, 1 December 2011 (UTC)
</div>

==== reserving other prefixes ====
We should '''reserve all other single-letter-dash prefixes for future use''' (within the scope of '''h-''' objects: outside of the context of an '''h-''' object, this is inapplicable).

In practice we have seen little (if any) use of single-letter-dash prefixing of class names by web developers/designers, and thus in practice we think this will have little if any impact/collisions. Certainly far fewer than existing generic microformat property class names like "title", "note", "summary".

==== existing single letter class prefixes ====
We should document existing usage of single/double letter prefixed names:
* Google+ (e.g. [https://plus.google.com/109182513536739786206 profile page], others) uses:
** '''a-'''
** '''d-'''
** '''g-''', '''gb*'''
* [http://getskeleton.com/#utilities Skeleton] uses
** '''u-''' for utility classes u-full-width u-max-full-width u-pull-right u-pull-left and u-cf
* [https://github.com/suitcss/utils SUITCSS] uses
** '''u-''' for utility classes. Usually two words written in camelCase: u-alignTop u-floatLeft however some use abbreviations: u-nbfc (new block formatting context) u-cf (clearfix)
* Yahoo
** '''y-'''
* others? please add alphabetical by company/org name.

== microformats 2 example ==
Example: taking that simple heading hCard example forward:

<source lang=html4strict>
<h1 class="h-card">Chris Messina</h1>
</source>

As part of microformats 2.0 we would immediately define root class names and property names for all existing microformats and drafts consistent with this naming convention, and require support thereof from all new implementations, as well as strongly encouraging existing implementations to adopt the simplified microformats 2.0 syntax and mechanism. Question: which microformats deserve explicit backward compatibility?

As a community we would continue to use the microformats [[process]] both for researching and determining the need for new microformats, and for naming new microformat property names for maximum re-use and interoperability of a shared vocabulary.

If it turns out we need a new property type in the future, we can use one of the remaining single-letter-prefixes to add it to microformats 2.0. This would require updating of parsers of course, but in practice the number of different types of properties has grown very slowly, and we know from other schema/programming languages that there's always some small limited number of scalar/atomic property types that you need, and using those you can create compound types/objects that represent richer / more complicated types of data.

=== ADVANTAGES ===
This has numerous advantages:
* '''better maintainability''' - much more obvious to web authors/designers/publishers which class names are for/from microformats.
* '''no chance of collision''' - for all practical purposes with existing class names and thus avoiding any need to add more complex CSS style rules to prevent unintended styling effects.
* '''simpler parsing''' - parsers can now do a simple stream-parse (or in-order DOM tree walk) and parse out '''all''' microformat objects, properties, and values, without having to know anything about any specific microformats.
* '''separation of syntax and vocabulary''' - by abstracting microformats 2 syntax independent of any vocabulary, it allows and encourages development of shared vocabularies that can work in alternative syntaxes.

More examples: here is that same heading example with name components:

<source lang=html4strict>
<h1 class="h-card">

Chris
<abbr class="p-additional-name">R.</abbr>
Messina

</h1>
</source>

with a hyperlink to Chris's URL:

<source lang=html4strict>
<h1 class="h-card">
<a class="p-fn u-url" href="http://factoryjoe.com/">
Chris
<abbr class="p-additional-name">R.</abbr>
Messina
</a>
</h1>
</source>

=== COMPATIBILITY ===

microformats 2.0 is backwards compatible in that it permits content authors to markup with both old and new class names for compatibility with old tools.

Here is a simple example:

<source lang=html4strict>
<h1 class="h-card vcard">
Chris Messina
</h1>
</source>

a microformats 2.0 parser would see the class name "h-card" and imply the one required property from the contents, while a microformats 1.0 parser would find the class name "vcard" and then look for the class name "fn". no data duplication is required. this is a very important continuing application of the <abbr title="don't repeat yourself">DRY</abbr> [[principle]].

And the above hyperlinked example with both sets of class names:

<source lang=html4strict>
<h1 class="h-card vcard">
<a class="p-fn u-url n fn url" href="http://factoryjoe.com/">
Chris
<abbr class="p-additional-name additional-name">R.</abbr>
Messina
</a>
</h1>
</source>

== vendor extensions ==
(this section was only discussed verbally and not written up during discussions - capturing here as it is topical)

Proprietary extensions to formats have typically been shortlived experimental failures with one big recent exception.

Proprietary or experimental CSS3 property implementations have been very successful.

There has been much use of border radius properties and animations/transitions which use CSS properties with vendor-specific prefixes like:

* -moz-border-radius
* -webkit-border-radius

etc.

Note that these are merely string '''prefixes''', not bound to any URL, and thus not namespaces in any practical sense of the word. This is quite an important distinction, as avoiding the need to bind to a URL has made them easier to support and use.

This use of vendor specific CSS properties has in recent years allowed the larger web design/development/implementor communities to experiment and iterate on new CSS features while the features were being developed and standardized.

The benefits have been two-fold:
* designers have been able to make more attractive sites sooner (at least in some browsers)
* features have been market / real-world tested before being fully standardized, thus resulting in better features

Implementers have used/introduced "x-" prefixes for IETF MIME/content-types for experimental content-types, MIME parameter extensions, and HTTP header extensions, per RFC 2045 Section 6.3, RFC 3798 section 3.3, and [https://secure.wikimedia.org/wikipedia/en/wiki/List_of_HTTP_header_fields#Common_non-standard_headers Wikipedia: HTTP header fields - non-standard headers] (could use RFC reference instead) respectively, like:

* application/x-latex (per [https://secure.wikimedia.org/wikipedia/en/wiki/Internet_media_type#Type_x Wikipedia Internet media type: Type x])
* x-spam-score (in email headers)
* X-Pingback (per [http://en.wikipedia.org/wiki/Pingback Wikipedia:Pingback])

Some standard types started as experimental "x-" types, thus demonstrating this experiment first, standardize later approach has worked for at least some cases:

* image/x-png (standardized as image/png, both per [http://tools.ietf.org/html/rfc2083 RFC2083])

There have been times when specific sites have wanted to extend microformats beyond what the set of properties in the microformat, and currently lack any '''experimental''' way to do so - to try and see if a feature (or even a whole format) is interesting in the real world before bothering to pursue researching and walking it through the microformats process. Thus:

'''Proposal:'''
* '*-x-' + '-' + meaningful name for root and property class names
** where "*" indicates the single-character-prefix as defined above
** where "x" indicates a literal 'x' for an experimental extension OR
** OR "x" indicates a vendor prefix (more than one character, e.g. like CSS vendor extension abbreviations, or some stock symbols, avoiding first words/phrases/abbreviations of microformats properties like dt-)
** e.g.
** "h-bigco-one-ring" - a hypothetical "bigco" vendor-specific "onering" microformat root class name.
** "p-goog-preptime" - to represent [http://www.google.com/support/webmasters/bin/answer.py?answer=173379 Google's "preptime" property extension] to [[hRecipe]] (aside: "duration" may be another property type to consider separate from "datetime" as it may be subject to different parsing rules.)
** "p-x-prep-time" - a possible experimental property name to be added to hRecipe upon consideration/documentation of real-world usage/uptake.

Background - this proposal is a composition of the following (at least somewhat) successful vendor extension syntaxes
* [http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords CSS 2.1 4.1.2.1 Vendor-specific extensions]
* IETF MIME/content-type "x-*" extensions per RFC 2045 Section 6.3. [http://en.wikipedia.org/wiki/Internet_media_type]
* IETF MIME experimental fields (e.g. x-spam-score)
* HTTP header extensions (e.g. x-pingback)
* note also [http://www.mnot.net/blog/2009/02/18/x- some critical thoughts from mnot]

== issues ==
=== Hungarian prefixing issues ===
Raised by [[User:BenWard|BenWard]] 01:16, 11 April 2011 (UTC)

Microformats 2.0 proposes using an explicit <code>[a-z]-</code> prefix on properties, to differentiate them from other uses of the class attribute, and identify them as microformat properties, such that they can be parsed generically.

* The differentiation use case is supported by anecdotal evidence of sites (such as Facebook, Twitter, Yahoo) removing microformats or breaking objects in page edits. The addition of a prefix assists self-documentation of code.
* The generic parsing use case is supported by Google Rich Snippets, Yahoo Search Monkey, and extensible plugins like Operator and the Firefox microformats parser. Although these extract microformats from the page, they are intermediate systems between the page content and the actual interpretation of the data. They need to parse all objects from a page, and then another developer or application will interpret some of them into something else.

(Note: the theoretical assertion "they need to parse all objects from a page" is not actually backed by *any* existing use of microformats/microdata/RDFa parsing - *none* of those parse "all objects from a page" if you consider every markup element an "object" - rather, one of the strength of microformats (mimicked by the others) is that the publisher is able to markup *just* the data to be extracted, rather than perhaps purely "presentational" content, ads, UI widgets etc. -- [[User:Tantek|Tantek]] 02:15, 11 April 2011 (UTC) )

The µf2 proposal goes further, though, into a small vocabulary of [http://en.wikipedia.org/wiki/Hungarian_notation Hungarian] prefixes of properties based on data type. This increases the level of understanding required to read microformats, and reduces the benefit of all microformat properties having a consistent identifying prefix.

(Debatable assertion:"increases the level of understanding required to read microformats" - how? In microformats 2.0, authors/developers know that any single-letter-and-hyphen prefixed class name is for microformats 2.0, in contrast to today - developers have consistently given feedback that's hard to tell which generic class names (other than h* names) are microformat related and which are not. As for specific prefixes, "h-*" is special and follows the pattern of existing microformats. p = generic (p)roperty, and the other prefixes have trivial mnemonics as well, d for (d)atetimes etc. (so far, hopefully we can keep that up). -- [[User:Tantek|Tantek]] 02:15, 11 April 2011 (UTC) )

Hungarian notation itself is controversial amongst programmers.
Plenty find it uglifies their code, can be a cause of confusion (especially when very-short prefixes are used, or esoteric types, or where the declared set of types differs from the available types in other programming languages.) Others support its benefits to type identification.

(Programmers are not the priority here, rather, designers/authors/publishers are. We design microformats for them first as they're the common use case, and we should avoid making statements that seem to imply any priority for the aesthetic preferences of programmers. -- [[User:Tantek|Tantek]] 02:15, 11 April 2011 (UTC))

Critically, however, there is no clear indication that either of the above use cases requires types to be strongly identified.

<div class="discussion">
* For identifying µf in pages, a differentiator is required from regular classnames. There is no evidence of further requirement to differentiate between properties beyond their name (and existing criticisms of Hungarian notation suggest it can harm understandability.)
** There is such evidence, and perhaps thus this would be a good FAQ topic. The derivation is quite simple - it comes directly from minimally affecting existing markup, and maximally using existing semantic information. Example of special purpose parsing, URL-like properties use the value of the 'href' (or equivalent) attribute because that's where that data already is in pages. Similarly with dates and datetimes - special parsing rules for that data type have permitted us to design the [[value-class-pattern]] to take advantage of specially parsing date and time separation. By re-using data *where publishers already put it, including attributes vs inline* we minimize the risk of data drift. -- [[User:Tantek|Tantek]] 02:15, 11 April 2011 (UTC)
** Additionally, this special type-specific parsing of microformats properties conveys microformats advantages of markup brevity that other syntaxes lack. E.g. you can convey *multiple* properties and values from a single existing element, e.g. the *very* common real-world pattern <code> <nowiki><a href="http://example.com/user">User Name</a></nowiki> </code> is minimally marked up as <code> <nowiki><a class="p-name u-url" href="http://example.com/user">User Name</a></nowiki> </code>
* For generic parsing, there is no requirement that datatypes be established at extraction time. Data types will instead be applied by the developers of apps and widgets that build on the generic parsers.
** There are requirements based on experience with actual markup. In order to support the patterns of where content publishers put the data we want to extract, we have determined (based on those publishing patterns) a few different ways (types) of parsing this data. This is all captured in the [[hcard-parsing]] property-specific parsing rules each of which were added one at a time as Brian Suda and myself encountered real world sites wanting to use [[hCard]] but not wanting to have to rewrite their markup (adding one span and some class names was about the limit, moving tags/attributes around was a showstopper in many/most cases), and each of the microformats 2.0 "types" are directly derived from such special purpose data/type parsing across *multiple* microformats. -- [[User:Tantek|Tantek]] 02:15, 11 April 2011 (UTC)
* A counter argument may be that special properties in microformats—such as URLs, or images—need to be identified because in microformats it is common to parse an attribute (href, or src) rather than inner text of an element for these properties. However, in the context of extracting and then interpreting HTML in other contexts this is insufficient: For example, though an image only exists as a single property in vcard, in HTML it is both a URL to a resource ''and'' and text string (alt) representing an accessible fallback. A ‘generic extracter’ of microformats from a page must capture all of this information from HTML, so that the interpreting application can choose which data type is most relevant to its context. Likewise, an application interpreting a URL may also consider using the original inner text as an inferred label. Both pieces of data are useful, and a generic parser should not discard elemental semantics at the extraction level.
** It's not just "*common* to parse an attribute rather than inner text of an element for these properties" - it is the vast overwhelming majority - if not all - such cases!
** One misconception: "image only exists as a single property". No, there is both 'photo' and 'logo'. The 'url' and 'sound' properties are also of type 'url'. For all of these, when parsing an "object" element, you must use the 'data' attribute first for example. hCalendar has "attachment" as well. Etc.
** Theoretical assertion: "A ‘generic extracter’ of microformats from a page must capture all of this information from HTML, so that the interpreting application can choose which data type is most relevant to its context." Why? There is no existing nor demonstrated use case for this requirement, even across other formats. While I agree it "might be nice" to develop a new "structured image" type - that's brand new work (deserving of research per the [[process]] etc.), and not a good source of reasoning to reject existing working patterns. I reject blocking microformats 2.0 on an as-yet-to-be-researched-enhancement. This is certainly a case where "better" is an enemy of the good.
** Theoretical assertion: "a generic parser should not discard elemental semantics at the extraction level" - already does for other syntaxes like both microdata and RDFa - so clearly this is not a reasonable "should not" assertion (and thus unnecessary) for development of a minimally competitive syntax. RDFa kind of cheats by overloading the 'rel' attribute in attempt to solve the name+url case as mentioned above, but that's only two types - and existing real world use of microformats has demonstrated utility of a few more. -- [[User:Tantek|Tantek]] 02:15, 11 April 2011 (UTC)
</div>

Given this, hungarian prefixes are of no benefit to parsers (and may in fact harm applications down the chain if parsing is prematurely strict.) It would be sufficient then not to concern embedding data types in property names, and instead settle on one single property prefix to differentiate all properties consistently. This would reduce the prefixes to just 3:

* <code>h</code> would indicates a root class name. An ‘object in HTML’.
* <code>p</code> would indicates a property within an object.
* <code>x</code> would indicates an experimental extension to an object.

--[[User:BenWard|BenWard]] 01:16, 11 April 2011 (UTC)

The primary benefit of type-specific parsing is *not* for parsers, but rather, publishers (who we still hold in higher priority than parsers).

I will also note that *each* of the type-specific parsing methods in [[hcard-parsing]] was added both conservatively, reluctantly, and only when it became clear that such type-specific publishing patterns existing across *multiple* sites that would otherwise be unable to change their markup to work with microformats (Yes, I'm wishing now that I better documented exactly *which* sites, precisely *when*, but like many startups, early on we didn't exactly know how much to document vs get things done - frankly I think we documented far more than any other comparable such efforts, e.g. we managed to at least capture/grow both an explicit [[process]] and [[principles]] in *far* greater detail than anything remotely comparable either before microformats or since!). The type-specific parsing features are certainly not overdesigned, on the contrary they've *slowly* evolved, adapting to real world data on the web.

While per the [[simplicity]] principle, I would actually *strongly* prefer to only have the three prefixes given above, or actually just *two* (I started with just two for the design of microformats 2.0 actually, just "h-*" and "p-*"), doing so would be a step *backwards* in terms of the adaptability of microformats to existing markup, and that's IMHO an unacceptable barrier, and a sufficiently high barrier to hurt the adoption/applicability of microformats 2.0.

(Aside: In addition, note that you still need h-x-* for experimental objects, and thus it's *simpler* to simply have *both* h-x-* and p-x-* rather than add x-*. Alternatively x-h-* and x-p-* is no better, in some ways worse, in that object vs. property is a more important distinction for parsers than established vs experimental, especially if/when an experimental property (or object) may be adopted. Also, mild precdent: PNG started with image/x-png, not x-image/png.).

To put it in a positive way, type-specific parsing conveys microformats a publisher-markup-density (and re-use) advantage which neither microdata nor RDFa have, and it would behoove us to *keep* this significant real-world advantage as we evolve microformats.

-- [[User:Tantek|Tantek]] 02:15, 11 April 2011 (UTC)

== see also ==
* [[microformats-2]]
* [[microformats-2-brainstorming]]
* [[microformats-2-prefixes]]
* [[microformats-2-faq]]

existing-rel-values

2015-03-13T15:47:51Z

Andy sky: /* HTML5 link type extensions */ Removed DCTERMS.identifier as explicitly stated to be in the "literal" range as defined in RDFa spec

<entry-title> existing rel values </entry-title>

This page contains tables of known HTML rel values from specifications, formats, proposals, brainstorms, and non-trivial [[POSH]] usage in the wild. In addition, dropped and rejected values are listed at the end for comprehensiveness.

usage: see [[rel-faq#How_is_rel_used|how is 'rel' used]]. Regarding rev, see: [[rel-faq#Should_rev_even_be_used|should 'rev' even be used]].

This page is also the official rel registry ([http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#other-link-types][http://www.w3.org/TR/html5/links.html#other-link-types]). Add new and proposed rel values to the following section:
* [[existing-rel-values#HTML5_link_type_extensions|HTML5 link type extension]]

== formats ==
These rel values are defined formats from specifications (HTML 4, microformats) are thus are recommended for general use. Alphabetically ordered by value.

Note:
* Do not add proposed rel values for HTML5 here, add them to the [[#HTML5_link_type_extensions|HTML5 link type extensions]] table.
* Do not add rel values you find in the wild to this table of rel formats, instead add them to the table in the [[existing-rel-values#POSH_usage|POSH section]].
* Do not add non-HTML rel values you find to this table of rel formats, instead add them to the table in the [[existing-rel-values#non_HTML_rel_values|non HTML rel values section]].
* Do not add rel values from obsolete/superceded proposals or drafts, instead add them to the table in the "dropped" section.

Sources:
* W3C Recommendations:
** [http://www.w3.org/TR/html401/types.html#h-6.12 HTML 4.01 section 6.12 Link types] (HTML4 Link types)
** [http://www.w3.org/TR/grddl/ Gleaning Resource Descriptions from Dialects of Languages] (GRDDL)
* [[microformats]] specifications
** [[xfn]]
** [[rel-license]]
** [[rel-nofollow]]

{| border="1"
|+
! Keyword
! Effect on <code>link</code>
! Effect on <code>a</code>, <code>area</code>
! Brief description (from the relevant specification where possible)
! Link to defining specification

|-
| [[rel-acquaintance|acquaintance]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be an acquaintance
| [[XFN]]

|-
| [[rel-alternate|alternate]]
| external resource
| external relation
| Designates substitute versions for the document in which the link occurs. When used together with the <code>lang</code> attribute, it implies a translated version of the document. When used together with the <code>media</code> attribute, it implies a version designed for a different medium (or media).
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-appendix|appendix]]
| allowed
| allowed
| Refers to a document serving as an appendix in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-bookmark|bookmark]]
| not allowed
| allowed
| Refers to a bookmark. A bookmark is a link to a key entry point within an extended document. The <code>title</code> attribute may be used, for example, to label the bookmark. Note that several bookmarks may be defined in each document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-chapter|chapter]]
| allowed
| allowed
| Refers to a document serving as a chapter in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-child|child]]
| not allowed
| external relation
| the referenced person is a child of the person represented by the current document
| [[XFN]]

|-
| [[rel-colleague|colleague]]
| not allowed
| external relation
| the referenced person is a colleague of the person represented by the current document
| [[XFN]]

|-
| [[rel-contact|contact]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be a contact
| [[XFN]]

|-
| [[rel-contents|contents]]
| allowed
| allowed
| Refers to a document serving as a table of contents. Some user agents also support the synonym ToC (from "Table of Contents").
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-copyright|copyright]]
| allowed
| allowed
| Refers to a copyright statement for the current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-co-resident|co-resident]]
| not allowed
| external relation
| the referenced person lives in the same residence as the person represented by the current document
| [[XFN]]

|-
| [[rel-co-worker|co-worker]]
| not allowed
| external relation
| the referenced person is a co-worker of the person represented by the current document
| [[XFN]]

|-
| [[rel-crush|crush]]
| not allowed
| external relation
| this person considers the referenced person to be a crush (i.e. has a crush on the referenced person)
| [[XFN]]

|-
| [[rel-date|date]]
| not allowed
| external relation
| this person considers the referenced person to be a date (i.e. is dating the referenced person)
| [[XFN]]

|-
| [[rel-friend|friend]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be a friend
| [[XFN]]

|-
| [[rel-glossary|glossary]]
| allowed
| allowed
| Refers to a document providing a list of terms and their definitions that pertain to the current document.||[http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-help|help]]
| allowed
| allowed
| Refers to a document offering help (more information, links to other sources information, etc.)
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-its-rules|its-rules]]
| allowed
| not allowed
| Refers to a document with external ITS rules.
| [http://www.w3.org/TR/its20/#selection-global-html5 Internationalization Tag Set (ITS) Version 2.0]

|-
| [[rel-kin|kin]]
| not allowed
| external relation
| the referenced person is part of the extended family of the person represented by the current document
| [[XFN]]

|-
| [[rel-license|license]]
| allowed
| allowed
| …indicates that the <nowiki>[referenced document]</nowiki> is a license for the current page.
| [[rel-license]]

|-
| [[rel-me|me]]
| external relation
| external relation
| the referenced document represents the same person as does the current document
| [[XFN]]

|-
| [[rel-met|met]]
| not allowed
| external relation
| this person has met the referenced person
| [[XFN]]

|-
| [[rel-muse|muse]]
| not allowed
| external relation
| the referenced person inspires the person represented by the current document
| [[XFN]]

|-
| [[rel-neighbor|neighbor]]
| not allowed
| external relation
| the referenced person lives nearby the person represented by the current document
| [[XFN]]

|-
| [[rel-next|next]]
| external relation
| external relation
| Refers to the next document in a linear sequence of documents. User agents may choose to preload the "next" document, to reduce the perceived load time.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-nofollow|nofollow]]
| not allowed
| external relation
| indicates that the destination of that hyperlink {{should-not}} be afforded any additional weight or ranking by user agents which perform link analysis upon web pages (e.g. search engines).
| [[rel-nofollow]]

|-
| [[rel-parent|parent]]
| not allowed
| external relation
| the referenced person is a parent of the person represented by the current document
| [[XFN]]

|-
| [[rel-prev|prev]]
| external relation
| external relation
| Refers to the previous document in an ordered series of documents. Some user agents also support the synonym "Previous".
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-previous|previous]]
| external relation
| external relation
| Synonym of <code>prev</code>
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-section|section]]
| allowed
| allowed
| Refers to a document serving as a section in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-sibling|sibling]]
| not allowed
| external relation
| the referenced person is a sibling of the person represented by the current document
| [[XFN]]

|-
| [[rel-spouse|spouse]]
| not allowed
| external relation
| the referenced person is a spouse of the person represented by the current document
| [[XFN]]

|-
| [[rel-start|start]]
| allowed
| allowed
| Refers to the first document in a collection of documents. This link type tells search engines which document is considered by the author to be the starting point of the collection.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-stylesheet|stylesheet]]
| external resource
| not allowed
| a style sheet for the current document used with the invisible <link href> element which is not ideal for content relationships. Content relationships should be user visible and thus uses with <a href> are strongly preferred. Unfortunately the use of stylesheet in user visible content like <a href> appears to be strictly theoretical.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-subsection|subsection]]
| allowed
| allowed
| Refers to a document serving as a subsection in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-sweetheart|sweetheart]]
| not allowed
| external relation
| this person considers the referenced person to be their sweetheart
| [[XFN]]

|-
| [[rel-tag|tag]]
| not allowed
| allowed
| …indicates that the <nowiki>[referenced document]</nowiki> is an author-designated "tag" (or keyword/subject) for the current page.
| [[rel-tag]]

|-
| [[rel-toc|toc]]
| allowed
| allowed
| Synonym of <code>contents</code> (from "Table Of Contents")
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-transformation|transformation]]
| allowed
| allowed
| Relates a source document to a transformation, usually represented in XSLT, that relates the source document syntax to the RDF graph syntax. Used in [[grddl|GRDDL]]
| [http://www.w3.org/TR/grddl/#transformation GRDDL]

|}

=== notes ===
*<code>rel="alternate"</code> can take further meaning from additional attributes, such as
** <code>rel="alternate" lang="fr"</code> (French language version of this page)
** <code>rel="alternate" media="print"</code> (printable version of this page)
** <code>rel="alternate" media="handheld"</code> (version of the page intended or better for handheld/portable devices like PDAs, cell phones, etc.)

*Synonyms such as "previous", "toc" are not as widely supported as the main term.

== proposals ==
A few rel values have been developed as drafts as a result of going through most of the microformats [[process]], and are thus listed here for your serious consideration. You may use these values, and if you find any problems with them please point them out on the respective "issues" page for the rel value.

{| border="1"
|+
! rel value !! summary !! proposed in !! external spec (if any)
|-
| [[rel-pronunciation|pronunciation]] || …indicates that the destination of the 'link' element is a document providing a pronunciation lexicon for speech-synthesis purposes. || [[rel-pronunciation]]
|-
| [[rel-directory|directory]] || …indicates that the destination of the hyperlink is a directory listing containing an entry for the current page. || [[rel-directory]]
|-
| [[rel-enclosure|enclosure]] || …indicates that the destination of that hyperlink is intended to be downloaded and cached. || [[rel-enclosure]] || [http://www.apps.ietf.org/rfc/rfc4287.html RFC4287]
|-
| [[rel-home|home]] || …indicates that the <nowiki>[referenced document]</nowiki> is the homepage of the site in which the current page appears. || [[rel-home]]
|-
| [[rel-payment|payment]] || …indicates that the destination of the hyperlink provides a way to show or give support (e.g. financial) for the current page|| [[rel-payment]]
|}

== HTML5 link type extensions ==

The following values are registered as link type extensions per the [http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#other-link-types requirements in the WHATWG HTML spec] and the [http://dev.w3.org/html5/spec/links.html#other-link-types requirements in the W3C HTML5 spec].

Before you register a new value:
* '''Please check the [[#formats|Formats table]] and DO NOT re-register''' rel values that are already there. Please note that the W3C HTML WG has made a [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Decision] to drop <code>index</code>, <code>up</code>, <code>first</code> and <code>last</code> from the HTML5 spec itself.
* '''Please check the [[#dropped|Dropped table]] and DO NOT register''' values that are already there. If you believe a rel value was dropped from another specification without prejudice, please provide link/cite to explicit text/decision stating as such, e.g. the value was merely postponed, or perhaps expected to be spun-out into its own spec from the group developing that specification.

Note that entries in the [[#formats|Formats table]] and entries that are already in HTML5 as built-in keywords are also considered extensions with the "Ratified" status.

Please make sure that registrations added here have all the required data filled in ''including'':
* "Effect on link"
* "Effect on a and area" and
* a link to a spec that documents the keyword ''as an HTML <code>rel</code> keyword''. (A spec that merely defines the file format of the link target but does not define the <code>rel</code> keyword for use in HTML is not the kind of spec that is being required here.)

Entries lacking any of the above required data will likely be removed.

Changes to this registry will not be reflected in validators in real time. But validators will typically get automatically updated with the changes within one week or so

{| border="1"
|+
! Keyword
! Effect on <code>link</code>
! Effect on <code>a</code>, <code>area</code>
! Brief description
! Link to specification
! Synonyms
! Status

|-
| [[rel-apple-touch-icon|apple-touch-icon]]
| External Resource
| Not allowed
| Specify a Webpage Icon for a “Web Clip”, or “touch icon”, for mobile devices (not limited to Apple devices).
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| probably redundant with rel=icon
| proposed

|-
| [[rel-apple-touch-icon-precomposed|apple-touch-icon-precomposed]]
| External Resource
| Not allowed
| Specify a Webpage Icon for a “Web Clip”, or “touch icon”, for mobile devices (not limited to Apple devices).
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| probably redundant with rel=icon
| proposed

|-
| [[rel-apple-touch-startup-image|apple-touch-startup-image]]
| External Resource
| Not allowed
| Specify a splashscreen for Web apps on iOS Safari
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| maybe redundant with rel=icon with the sizes attribute?
| proposed

|-
| [[rel-attachment|attachment]]
| Hyperlink
| Hyperlink
| The resource linked to is "attached" to this document, similar to email attachments. Used in WordPress.
| No formal specification
|
| proposed

|-
| [[WPVL_PRETTYPHOTO_REL]]
| Hyperlink
| Hyperlink
| Open lightbox with video
| No formal specification
|
| proposed

|-
| [[rel-authorization_endpoint|authorization_endpoint]]
| External Resource
| Not allowed
| Specify a hosted authorization server
| [http://indiewebcamp.com/distributed-indieauth distributed IndieAuth documentation]
|
| proposed

|-
| [[rel-canonical|canonical]]
| External Resource
| Not allowed
| Specifies the canonical URL for the current document in order to help avoid duplicate content.
| [http://en.wikipedia.org/wiki/Canonical_meta_tag Canonical meta tag] [http://www.Google.com/support/webmasters/bin/answer.py?answer=139066#2 Canonicalization at Google Webmaster Central] [http://www.Bing.com/community/site_blogs/b/webmaster/archive/2009/02/12/partnering-to-help-solve-duplicate-content-issues.aspx Microsoft Webmaster Center] [http://www.YSearchBlog.com/2009/02/12/fighting-duplication-adding-more-arrows-to-your-quiver/ Yahoo! Search Blog]
|
| proposed

|-
| [[rel-category|category]]
| Hyperlink
| Hyperlink
| Refers to a category assigned to the current document or post. Implemented by WordPress for indicating a relation between a blog post and a category.
| [[rel-category]]
|
| proposed

|-
| [[rel-component|component]]
| External Resource
| Not allowed
| Specify an HTML document that is treated as a component of this document.
| [https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/components/index.html Web Components]
|
| proposed

|-
| [[rel-chrome-webstore-item|chrome-webstore-item]]
| External Resource
| Not allowed
| Link tag to declare for app and extensions inline installations hosted in the Chrome Web Store.
| [https://developers.google.com/chrome/web-store/docs/inline_installation Using Inline Installation]
|
| proposed

|-
| [[rel-dcterms.(property)#conformsTo|DCTERMS.conformsTo]]
| External Resource
| Not allowed
| An established standard to which the described resource conforms. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.conformsTo" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#contributor|DCTERMS.contributor]]
| External Resource
| Not allowed
| An entity responsible for making contributions to the resource. Examples include a person, an organization, or a service. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.contributor" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#creator|DCTERMS.creator]]
| External Resource
| Not allowed
| An entity primarily responsible for making the resource. Examples include a person, an organization, or a service. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.creator" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#description|DCTERMS.description]]
| External Resource
| Not allowed
| An account of the resource. Description may include but is not limited to: an abstract, a table of contents, a graphical representation, or a free-text account of the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.description" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#hasFormat|DCTERMS.hasFormat]]
| External Resource
| Not allowed
| A related resource that is substantially the same as the pre-existing described resource, but in another format. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#hasPart|DCTERMS.hasPart]]
| External Resource
| Not allowed
| A related resource that is included either physically or logically in the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#hasVersion|DCTERMS.hasVersion]]
| External Resource
| Not allowed
| A related resource that is a version, edition, or adaptation of the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isFormatOf|DCTERMS.isFormatOf]]
| External Resource
| Not allowed
| A related resource that is substantially the same as the described resource, but in another format. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isPartOf|DCTERMS.isPartOf]]
| External Resource
| Not allowed
| A related resource in which the described resource is physically or logically included. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isReferencedBy|DCTERMS.isReferencedBy]]
| External Resource
| Not allowed
| A related resource that references, cites, or otherwise points to the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isReplacedBy|DCTERMS.isReplacedBy]]
| External Resource
| Not allowed
| A related resource that supplants, displaces, or supersedes the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isRequiredBy|DCTERMS.isRequiredBy]]
| External Resource
| Not allowed
| A related resource that requires the described resource to support its function, delivery, or coherence. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isVersionOf|DCTERMS.isVersionOf]]
| External Resource
| Not allowed
| A related resource of which the described resource is a version, edition, or adaptation. Changes in version imply substantive changes in content rather than differences in format. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#license|DCTERMS.license]]
| External Resource
| Not allowed
| A legal document giving official permission to do something with the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.license" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#mediator|DCTERMS.mediator]]
| External Resource
| Not allowed
| An entity that mediates access to the resource and for whom the resource is intended or useful. In an educational context, a mediator might be a parent, teacher, teaching assistant, or care-giver. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.mediator" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#publisher|DCTERMS.publisher]]
| External Resource
| Not allowed
| An entity responsible for making the resource available. Examples include a person, an organization, or a service. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.publisher" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#references|DCTERMS.references]]
| External Resource
| Not allowed
| A related resource that is referenced, cited, or otherwise pointed to by the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#relation|DCTERMS.relation]]
| External Resource
| Not allowed
| A related resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#replaces|DCTERMS.replaces]]
| External Resource
| Not allowed
| A related resource that is supplanted, displaced, or superseded by the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#requires|DCTERMS.requires]]
| External Resource
| Not allowed
| A related resource that is required by the described resource to support its function, delivery, or coherence. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#rightsHolder|DCTERMS.rightsHolder]]
| External Resource
| Not allowed
| A person or organization owning or managing rights over the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.rightsHolder" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#source|DCTERMS.source]]
| External Resource
| Not allowed
| A related resource from which the described resource is derived. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#subject|DCTERMS.subject]]
| External Resource
| Not allowed
| The topic of the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-disclosure|disclosure]]
| Not allowed
| External Resource
| The 'disclosure' Link Relation Type designates a list of patent disclosures or a particular patent disclosure itself made with respect to material for which such relation type is specified.
| [http://tools.ietf.org/html/draft-yevstifeyev-disclosure-relation The 'disclosure' Link Relation Type]
|
| proposed

|-
| [[rel-discussion|discussion]]
| Hyperlink
| Hyperlink
| Refers to discussion of the current document or post.
| [[rel-discussion]]
|
| proposed

|-
| [[rel-dns-prefetch|dns-prefetch]]
| External Resource
| Not allowed
| Tells the browser to perform dns lookup for host names ahead of use.
| [https://developer.mozilla.org/En/Controlling_DNS_prefetching Mozilla documentation] [http://dev.chromium.org/developers/design-documents/dns-prefetching Google documentation]
|
| proposed

|-
| [[rel-edit|edit]]
| Hyperlink
| Not allowed
| Tells the browser where the current page can be edited
| [http://universaleditbutton.org/Registered_MIME_type#Alternate_Linking_Scheme Universal Edit Button Alternate Linking Scheme]. Implemented in at least [http://mediawiki.org MediaWiki].
|
| proposed

|-
| [[rel-edituri|EditURI]]
| External Resource
| Not allowed
| A blogging auto discovery value, commonly used by WordPress
| [http://bitworking.org/projects/atom/draft-gregorio-09.html#Edit AtomAPI]
|
| proposed

|-
| [[rel-enclosure|enclosure]]
| External Resource
| External Resource
| Indicates that the referred resource is intended to be downloaded and cached.
| [[rel-enclosure]]
|
| proposed

|-
| [[rel-entry-content|entry-content]]
| Not allowed
| External Resource
| Indicates that the referenced document is an alternative display source for an Internet Explorer Web Slice.
| [http://msdn.microsoft.com/en-us/library/cc304073(VS.85).aspx#_alternative Web Slice format specification 0.9]
|
| proposed

|-
| [[rel-external|external]]
| Not allowed
| Hyperlink
| Indicates that the referenced document is not part of the same site as the current document.
| [[rel-external]]
|
| proposed

|-
| [[rel-home|home]]
| Hyperlink
| Hyperlink
| Refers to the top level document for the current document. It can be combined with 'alternate' to indicate a feed for the site of the current page.
| [[rel-home]]
|
| proposed

|-
| [[rel-hub|hub]]
| Hyperlink
| Hyperlink
| Refers to a hub that enables registration for notification of updates to the current page.
| [http://pubsubhubbub.googlecode.com/svn/trunk/pubsubhubbub-core-0.3.html#discovery PubSubHubbub Spec]
|
| proposed

|-
| [[rel-in-reply-to|in-reply-to]]
| Hyperlink
| Hyperlink
| Refers to an original post that the current page is a comment on or reply to.
| [[rel-in-reply-to]]
|
| proposed

|-
| [[rel-index|index]]
| Hyperlink
| Hyperlink
| Refers to a document providing a list of topics with pointers that pertain to the current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
|
| proposed

|-
| [[rel-indieauth|indieauth]]
| External Resource
| Not allowed
| the IndieAuth server for the relying party to contact for IndieAuth authentication
| [http://spec.indieauth.com/ IndieAuth specification]
|
| proposed

|-
| [[rel-issues|issues]]
| Hyperlink
| Hyperlink
| Refers to issues regarding the current document or specification.
| [[rel-discussion]]
|
| proposed

|-
| [[rel-lightbox|lightbox]]
| Not allowed
| Img Pop-Up
| Images with this attribute are displayed in a larger way than embedded in a website (or how you specified it) when clicked (e.g. with installed "Lightbox 2"-Plugin). When adding [group] to rel="lightbox" all images get a clickable button for next/prev; insert into <code><a rel="lightbox[group]"><img src="http:example.com/img.jpg"></a></code>
| [http://lokeshdhakar.com/projects/lightbox2/ Lightbox 2] (needs actual specification to be kept in this list, this link is just documentation of one implementation)
|
| proposed

|-
| [[rel-manifest|manifest]]
| External Resource
| Not allowed
| Imports or links to a manifest
| [http://w3c.github.io/manifest/#linking W3C Manifest for web application]
|
| proposed

|-
| [[rel-meta|meta]]
| External Resource
| Not allowed
| External metadata about the HTML document
| [http://www.w3.org/TR/2004/REC-rdf-syntax-grammar-20040210/#section-rdf-in-HTML W3C's RDF/XML Syntax Specification]
|
| proposed

|-
| [[rel-indieauth|micropub]]
| External Resource
| Not allowed
| the micropub endpoint for creating new posts
| [http://indiewebcamp.com/micropub Micropub scecification]
|
| proposed

|-
| [[rel-openid.delegate|openid.delegate]]
| External Resource
| Not allowed
| When the page that contains the link is used as an OpenID indentifier, the relying party perform sOpenID 1.1 authentication with the link target as the identifier instead.
| [http://openid.net/specs/openid-authentication-1_1.html#delegating_authentication OpenID Authentication 1.1]
|
| proposed

|-
| [[rel-openid.server|openid.server]]
| External Resource
| Not allowed
| The OpenID server for the relying party to contact for OpenID 1.1 authentication
| [http://openid.net/specs/openid-authentication-1_1.html#anchor4 OpenID Authentication 1.1]
|
| proposed

|-
| [[rel-openid2.local_id|openid2.local_id]]
| External Resource
| Not allowed
| When the page that contains the link is used as an OpenID indentifier, the relying party perform sOpenID 2.0 authentication with the link target as the identifier instead.
| [http://openid.net/specs/openid-authentication-2_0.html#rfc.section.7.3.3 OpenID Authentication 2.0]
|
| proposed

|-
| [[rel-openid2.provider|openid2.provider]]
| External Resource
| Not allowed
| The OpenID server for the relying party to contact for OpenID 2.0 authentication
| [http://openid.net/specs/openid-authentication-2_0.html#rfc.section.7.3.3 OpenID Authentication 2.0]
|
| proposed

|-
| [[rel-p3pv1|p3pv1]]
| External Resource
| Not allowed
| References a machine-readable privacy policy description in the P3P format
| [http://www.w3.org/TR/P3P/#syntax_link P3P spec]
|
| proposed

|-
| [[rel-pgpkey|pgpkey]]
| External Resource
| Not allowed
| Associates a PGP key with a Web page so that the Web page URL can be used as the commenter's URL in PGP-signed blog comments and the blogging system receiving the comment can fetch the key and verify the signature as belonging to the owner of the URL.
| [http://golem.ph.utexas.edu/~distler/blog/archives/000320.html PGP-Signed Comments]
|
| proposed

|-
| [[rel-pingback|pingback]]
| External Resource
| Not allowed
| gives the address of the pingback server that handles pingbacks to the current document
| [http://www.hixie.ch/specs/pingback/pingback Pingback]
|
| proposed

|-
| [[rel-prerender|prerender]]
| External Resource
| External Resource
| Prerenders the Web page targeted by the link including running it scripts.
| [[rel-prerender]]
|
| proposed

|-
| [[rel-profile|profile]]
| External Resource
| Contextual External Resource
| indicate[s] that the destination of that hyperlink is a metadata profile (e.g. an [[XMDP]] profile) for the current page or portion thereof. See also [[xmdp-brainstorming]].
| [http://microformats.org/wiki/rel-profile rel-profile]
|
| proposed

|-
| [[rel-publisher|publisher]]
| External Resource
| External Resource
| Indicates that the referenced document is a metadata profile (e.g., a social-media/real-name profile such as a Google+ profile) for the publisher of the current page, or some portion of the current page.
| [https://support.google.com/plus/answer/1713826?hl=en Google help page]
|
| proposed

|-
| [[rel-rendition|rendition]]
| External Resource
| External Resource
| Indicates some example rendering, interpretation, or depiction of the source. User agents may choose to execute, display, or render the target in-place; or navigate to the target.
| [http://www.globalmentor.com/specs/html-rel-rendition/ HTML rel rendition]
|
| proposed

|-
| [[rel-reply-to|reply-to]]
| External Resource
| Hyperlink
| indicates any mailbox(es) (i.e. email addresses) to which responses are to be sent. ''Note: this is distinct from the 'in-reply-to' value which refers to the originating document, not to the address where comments should be sent.
| [http://tools.ietf.org/html/rfc2822 RFC2822] (originally [http://tools.ietf.org/html/rfc822#section-4.4.3 RFC822])
|
| ratified

|-
| [[rel-service|service]]
| External Resource
| Not allowed
| Atom Publishing Protocol editing service autodiscovery.
| [http://wiki.whatwg.org/wiki/ServiceRelExtension Documentation on the WHATWG wiki]
|
| proposed

|-
| [[rel-shortlink|shortlink]]
| External Resource
| Not allowed
| Specifies the preferred shortened URL for the page.
| [http://code.google.com/p/shortlink/wiki/Specification shortlink spec]
|
| proposed

|-
| [[rel-sidebar|sidebar]]
| Hyperlink
| Hyperlink
| Indicates that the referenced document is intended to be shown in a secondary browsing context.
| [[rel-sidebar]]
|
| proposed

|-
| [[rel-sitemap|sitemap]]
| External Resource
| Not allowed
| Provides a link to an XML document describing the layout of the site.
| [[rel-sitemap]]
|
| proposed

|-
| [[rel-subresource|subresource]]
| External Resource
| Not allowed
| An external resource intended for use within the current page.
| [http://www.chromium.org/spdy/link-headers-and-server-hint/link-rel-subresource Chromium documentation]
|
| proposed

|-
| [[rel-syndication|syndication]]
| Hyperlink
| Hyperlink
| Refers to a page which is a syndicated copy of the current page.
| [[rel-syndication]]
|
| proposed

|-
| [[rel-timesheet|timesheet]]
| External Resource
| Not allowed
| Applies a timesheet to the document.
| [http://www.w3.org/TR/timesheets/#smilTimesheetsNS-Elements-Timesheet non-normative section in the Timesheet spec]
|
| proposed

|-
| [[rel-token_endpoint|token_endpoint]]
| External Resource
| Not allowed
| Specify an HTTP endpoint that micropub clients can use to obtain an access token given an authorization code
| [http://indiewebcamp.com/token-endpoint token endpoint documentation]
|
| proposed

|-
| [[rel-webmention|webmention]]
| External Resource
| Hyperlink
| gives the address of the webmention endpoint that handles webmentions to the current document
| [http://webmention.org/ WebMention specification]
|
| proposed

|-
| [[rel-widget|widget]]
| External Resource
| External Resource
| Autodiscovery for W3C widgets
| [http://dev.w3.org/2006/waf/widgets/Overview.html#linking-to-a-widget-package-from-a-html- non-normative section in the Widget packaging spec]
|
| proposed

|-
| [[rel-wlwmanifest|wlwmanifest]]
| External Resource
| Not allowed
| Windows Live Writer manifest autodiscovery
| [http://msdn.microsoft.com/en-us/library/bb463263.aspx documentation on MSDN]
|
| proposed

|-
| [[rel-image_src|image_src]]
| External Resource
| Not allowed
| Specify a Webpage Icon for use by Facebook, Yahoo, Digg, etc.
| Unknown, but see for instance [http://www.niallkennedy.com/blog/2009/03/enhanced-social-share.html this]
| probably redundant with rel=icon
| proposed

|-
| [[rel-cmis-acl|http://docs.oasis-open.org/ns/cmis/link/200908/acl]]
| External Resource
| External Resource
| Identifies the resource containing a CMIS ACL document for the link context
| [http://docs.oasis-open.org/cmis/CMIS/v1.0/cs01/cmis-spec-v1.0.html#_Toc243905525 CMIS 1.0, Section 3.4.3.4]
|
| proposed

|-
| [[rel-stylesheet/less|stylesheet/less]]
| External Resource
| Not allowed
| Less CSS framework stylesheets.
| [http://lesscss.org/#-client-side-usage Less CSS usage]
|
| proposed

|}

== brainstorming ==
Several rel values are being brainstormed as potential microformats and are thus listed here. If you find you have a use for such semantics in real world examples, consider trying out these values and provide feedback on the respective brainstorming page(s) with your results and experiences.

You may list new proposed rel values here, and even better if you can list and link to POSH uses in the wild.

{| border="1"
|+
! rel value !! summary !! brainstormed in and usage in the wild

|-
| [[rel-accessibility|accessibility]] || indicate[s] that the destination of that hyperlink contains accessibility information for the current page. || [http://www.brucelawson.co.uk/2009/rel-accessibility/ blog post] which itself uses the rel value in a <link> tag in the head of the document.

|-
| [[rel-author|author]] || indicate[s] that the destination of that hyperlink represents the author of the current page. Combines with [[rel-me|rel-me]] to chain authorship information. || Google has said it will index rel-Author in this [http://googlewebmastercentral.blogspot.com/2011/06/authorship-markup-and-web-search.html blog post], with further [http://www.google.com/support/webmasters/bin/answer.py?answer=1229920 discussion of the rel-me connection] See also [http://dev.w3.org/html5/spec/Overview.html#link-type-author the HTML5 spec]

|-
| [[rel-bibliography|bibliography]] || indicate[s] that the destination of that hyperlink is a bibliography for the current page. || [http://microformats.org/discuss/mail/microformats-discuss/2007-October/010863.html mailing list post, 2007-10-15]

|-
| [[rel-cite|cite]] || indicate[s] that the destination of that hyperlink is an authoritative source or a precedent to the current page. || [[distributed-conversation-brainstorming]]

|-
| [[rel-group|group]] || the referenced document represents a group to which the person represented by the current document belongs || [[group-brainstorming]]

|-
| [[rel-jslicense|jslicense]]
| Refers to a document with JavaScript source code and license information (also called a [http://www.gnu.org/licenses/javascript-labels.html JavaScript License Web Labels] page). We might want choose a keyword for this that is more general -- there are many situations besides JavaScript in which it is desirable or required by license agreements (e.g., GNU GPL) to make an offer of both the source code and a copy of a license when distributing object code versions of a given work.
|* Brainstorming page -- thoughts on the name?
* Ex. [http://www.eff.org EFF.org] (on <code>link</code>)
* Ex. [http://www.fsf.org FSF.org] (on <code>a</code>)
|-
| [[rel-longdesc|longdesc]] || Alternative to the img longdesc attribute, for use on visible links || [http://www.google.com/search?q=rel%3D%22longdesc%22 Google search for rel=longdesc in the wild] shows many sources of proposals. Please edit this to list the earliest and perhaps most recent/comprehensive proposal. No known real world POSH usage in the wild yet.

|-
| [[rel-map|map]] || Link to a map. Possibly embedded within an adr, hCard, geo or hCalendar. Parsers {{may}} attempt to parse the URL if it is a link to a known map site (e.g. Geohash, Google Maps, Multimap) and extract co-ordinates and other useful data. || (to [[User:TobyInk|TobyInk]] by email)

|-
| [[rel-member|member]] || the referenced document represents a member of the group represented by the current document || [[group-brainstorming]]

|-
| [[rel-m_PageScroll2id|m_PageScroll2id]] || JS to scroll to a defined ID || [[group-brainstorming]]

|-
| [[rel-preconnect|preconnect]] || indicates an origin that will be used to fetch required resources. Initiating an early connection, which includes the DNS lookup, TCP handshake, and optional TLS negotiation, allows the user agent to mask the high costs of connection establishment latency.|| [https://igrigorik.github.io/resource-hints/#preconnect resource hints draft]

|-
| [[rel-prefetch|prefetch]] || indicates the URL and content-type of a resource that is likely to be a required resource when the next action or navigation is triggered. Initiating an early fetch allows the user agent to mask the request latency of the resource and make it available sooner to the application.|| [https://igrigorik.github.io/resource-hints/#prefetch resource hints draft]

|-
| [[rel-preload|preload]] || indicates the URL and content-type of a resource that should be fetched as early as possible by the user agent. Initiating an early fetch allows the user agent to mask the request latency of the resource and make it available sooner to the application.|| [https://igrigorik.github.io/resource-hints/#preload resource hints draft]

|-
| [[rel-prerender|prerender]] || indicates the URL of the next navigation target. Initiating a prerender allows the user agent to deliver an instant navigation experience: the user agent downloads the top-level resource and its assets, and performs all of the processing steps required to show the page without actually showing it to the user.|| [https://igrigorik.github.io/resource-hints/#prerender resource hints draft]

|-
| [[rel-profile|profile]] || indicate[s] that the destination of that hyperlink is a metadata profile (e.g. an [[XMDP]] profile) for the current page or portion thereof || [[xmdp-brainstorming]]

|-
| [[rel-shortlink|shortlink]] || the referenced document represents the current document but with a shorter URL || [http://samj.net/2009/04/introducing-relshort-better-alternative.html blog post]
|-
| source || the referenced document represents the source code for the current document or project || [[source-brainstorming]] [http://adactio.com/journal/6667/ blog post]

|-
| vcalendar-parent || link from an event to a containing event || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]
|-
| vcalendar-child || link from an event to a contained event || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]
|-
| vcalendar-sibling || link from an event to a related event with the same container || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]

|-
| [[rel-status|status]] || the referenced document represents the status (or source of status updates) for the author of this document || [http://monkinetic.com/2009/11/24/status-autodiscovery-relstatus.html blog post]

|}

=== more brainstorming ===
See also:
* [[genealogy-brainstorming]] for some thoughts on possible additional values for family relationships (use existing [[XFN]] [[rel-parent|parent]], [[rel-child|child]], [[rel-sibling|sibling]], [[rel-spouse|spouse]], [[rel-kin|kin]] values first though)
* [[xpn-brainstorming]] for some thoughts on possible additional values for professional relationships (use existing [[XFN]] [[rel-co-worker|co-worker]], [[rel-colleague|colleague]] values first though)

== POSH usage ==
There are numerous rel values used as [[POSH]], both in the wild, whose origins are not necessarily known, nor are their meanings consistent. There are also numerous rel values from external proposals of varying degrees of merit. It is useful to document their existence and summarize their implied meanings/usage intent as research that may be used to perhaps take one or more of them thru the microformats [[process]] if there is both sufficient interest and sufficient in the wild usage.

Note: If a value is missing from this table, it may have either already been promoted by writing it up as a proposal, or demoted by being explicitly dropped. Please check the other tables first before adding to this table.

Note: this list is incomplete, please help complete it from the following sources:

External sources:
* [http://developer.mozilla.org/about/meta Meta Information in DevMo Docs] (DevMo)
* [http://wiki.mozilla.org/Microsummaries Microsummary]
* [http://lachy.id.au/dev/markup/specs/wclr/ Web Communication Link Relationships] (WCLR)
* [http://www.w3.org/MarkUp/Relationships.html W3C Link Relationship values draft] (LRdraft) - from a draft of the HTML spec circa 1991.
* [http://www.whatwg.org/specs/web-apps/current-work/multipage/section-links.html#linkTypes HTML5 draft] '''Liable to change'''
* [http://wiki.foaf-project.org/Autodiscovery FOAF Project Wiki: Autodiscovery] (FOAF)
* [http://www.apps.ietf.org/rfc/rfc4685.html RFC4685]
* [http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html Google Blog]

{| border="1"
|+
! rel value !! summary !! origin !! proposal(s)

|-
| [[rel-archive|archive]] || index of archived entries || unknown, perhaps Wordpress open source blogging software || WCLR

|-
| [[rel-archives|archives]] || Provides a link to a collection of records, documents, or other materials of historical interest. || || HTML5

|-
|[[rel-author|author]]||see brainstorming above for suggested use by google||unknown || DevMo / HTML5

|-
| [[rel-canonical|canonical]] || To help search engines disambiguate the same page with multiple representations || Google || [http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html Google]/[http://www.bing.com/community/blogs/webmaster/archive/2009/02/12/partnering-to-help-solve-duplicate-content-issues.aspx Microsoft]/[http://www.ysearchblog.com/2009/02/12/fighting-duplication-adding-more-arrows-to-your-quiver/ Yahoo!], [http://blog.ask.com/2009/02/ask-is-going-canonical.html Ask Jeeves]

|-
| [[rel-comment|comment]] || … || … || WCLR

|-
| [[rel-contribution|contribution]] || … || … || WCLR

|-
| [[rel-edituri|EditURI]]
| Location of the xml-rpc gateway for a Wordpress install that allows external programs to add, edit and delete posts. Used by "[http://codex.wordpress.org/Weblog_Client WordPress blog client]" software for automating posting and updating blog content from your desktop. || Seen in [http://www.wordpress.org/ WordPress], e.g. [http://www.tom-watson.co.uk/]. || Description stubbed in [[rel-edituri]].

|-
| [[rel-endorsed|endorsed]] || … || … || WCLR

|-
| [[rel-fan|fan]] || xxxx. || … || [[hcard-user-profile-authoring]]

|-
| [[rel-feed|feed]] || Gives the address of a syndication feed for the current document. || … || WCLR/ HTML5

|-
| [[rel-footnote|footnote]] || Location of the footnote on a link to a footnote. || Markdown preprocessors such as [http://maruku.rubyforge.org/ Maruku] || HTML5

|-
| [[rel-icon|icon]] || Imports an icon to represent the current document. (Allowed in <code>link</code> only) || [http://dev.w3.org/html5/spec-LC/links.html#rel-icon HTML5] || WCLR/HTML5

|-
| [[rel-kinetic-stylesheet|kinetic-stylesheet]] || Imports a [http://kssproject.org/ KSS] 'kinetic stylesheet' to bind dynamic behavior to elements || Used in the [http://plone.org Plone] Content Management System || …

|-
| [[rel-lightbox|lightbox]] || Hook - Indicates that following the link will trigger a "lightbox" script (Allowed in <code>link</code> only) || ([http://www.google.co.uk/search?q=rel%3D%22lightbox%22 Google search for rel=lightbox in the wild]) || …

|-
| [[rel-lightbox|lightbox[group_name]]] || Used by lightbox scripts to group different sets of images together. Images from one group will not appear in another group's lightbox. See also "lightbox". || [http://lokeshdhakar.com/projects/lightbox2/#how Lightbox 2] || …

|-
| [[rel-prettyPhoto|prettyPhoto]] || See also "lightbox" || ([http://www.google.fr/search?q=rel%3D%22prettyphoto%22 Google search for rel="prettyphoto" in the wild]) || …

|-
| [[rel-clearbox|clearbox]] || See also "lightbox" || ([http://www.google.fr/search?q=rel%3D%22clearbox%22 Google search for rel="clearbox" in the wild]) || …

|-
| [[rel-made|made]] || … || … || LRdraft

|-
| [[rel-meta|meta]] || … || [http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/#transport 1999 W3C RDF syntax REC] || FOAF

|-
| [[rel-microsummary|microsummary]]|| … || … ||[http://wiki.mozilla.org/Microsummaries Microsummary], be aware of: [[page-summary-formats#Issues_2|microsummary issues]]

|-
| [[rel-noreferrer|noreferrer]] || indicates that no referrer information is to be leaked when following the link. || [http://dev.w3.org/html5/spec-LC/links.html#rel-noreferrer HTML5] || HTML5

|-
| [[rel-openid-delegate|openid.delegate]] || … || ([http://www.google.co.uk/search?q=%22rel%3Dopenid%22 Google search for rel=openid.* in the wild]) || …

|-
| [[rel-openid-server|openid.server]] || … || ([http://www.google.co.uk/search?q=%22rel%3Dopenid%22 Google search for rel=openid.* in the wild]) || …

|-
| [[rel-permalink|permalink]] || … || … || WCLR

|-
| [[rel-pgpkey|pgpkey]] || (see also rel-publickey) || … || [http://golem.ph.utexas.edu/~distler/blog/archives/000320.html], [http://golem.ph.utexas.edu/~distler/blog/archives/000325.html]

|-
| [[rel-pingback|pingback]] || Gives the address of the pingback server that handles pingbacks to the current document. (Allowed in <code>link</code> only) || … || WCLR/ HTML5

|-
| [[rel-popover|popover]] || Used by a JS widget to display a large, descriptive tooltip. || [http://twitter.github.com/bootstrap Twitter's Bootstrap] [http://twitter.github.com/bootstrap/javascript.html#popovers Popover.js] || …

|-
| [[rel-prefetch|prefetch]] || Specifies that the target resource should be pre-emptively cached. (Allowed in <code>link</code> only) || … || HTML5

|-
| [[rel-privacy|privacy]] || Specifies that the target resource is the privacy policy. || … || …

|-
| [[rel-publickey|publickey]] || (see also rel-pgpkey) || … || [http://rasterweb.net/raster/2002/12/12/20021212072812/]

|-
| [[rel-referral|referral]] || … || … || WCLR

|-
| [[rel-related|related]] || … || … || WCLR

|-
| [[rel-replies|replies]] || indicates a continued thread || unknown || [http://www.apps.ietf.org/rfc/rfc4685.html RFC4685]

|-
| [[rel-resource|resource]] || … || … || WCLR

|-
| [[rel-search|search]] || … || unknown || unknown

|-
| [[rel-sitemap|sitemap]] || Links to a site map document. || … || http://www.sitemaps.org/

|-
| [[rel-sponsor|sponsor]] || … || … || WCLR

|-
| [[rel-tooltip|tooltip]] || Used by a JS widget to display a tooltip similar (though more customizable) to what is shown by browsers if the 'title' attribute is present. || [http://twitter.github.com/bootstrap Twitter's Bootstrap] [http://twitter.github.com/bootstrap/javascript.html#tooltips Tooltip.js] (and likely other JS tools) || …

|-
| [[rel-trackback|trackback]] || … || unknown, perhaps open source Movable Type blogging software || WCLR

|-
| [[rel-unendorsed|unendorsed]] || (probably redundant to [[rel-nofollow|nofollow]]) || … || WCLR

|-
| [[rel-user|user]] || … || … || WCLR
|-
| [[rel-wlwmanifest|wlwmanifest]] || Used by "[http://explore.live.com/windows-live-writer Windows Live Writer]," a Microsoft [http://codex.wordpress.org/Weblog_Client blog client] for automating posting and updating blog content from your desktop. || Seen in [http://www.wordpress.org/ WordPress], e.g. [http://www.tom-watson.co.uk/]. Similar values are probably used by other blog content management systems as well. || …

|}

=== WCLR ===

The WCLR proposal is described by its author (in e-mail, 2007-09-25) as:

<blockquote>
…now effectively obsolete, since HTML5 and Microformats cover all the worthwhile relationships in that already.

These are [http://www.whatwg.org/specs/web-apps/current-work/multipage/section-links.html#linkTypes covered by HTML5 already]:

* permalink -> bookmark
* archive -> archives
* feed
* pingback
* unendorsed -> nofollow

The rest now seem unnecessary.
</blockquote>

Nonetheless, there may be some mileage in using them in microformats, at least until HTML5 is widely available.

== Dublin Core ==
In the past, Dublin Core values have been added to this page in the table about HTML5 features, but no examples, nor an actual specification explicitly stating how the value(s) should be used in HTML could be found. The linked specifications below have been updated so we should start considering Dublin Core values accordingly.

{| border="1"
|+
! rel value !! summary !! source
|-
| schema.DC || a specification of all metadata terms maintained by the Dublin Core Metadata Initiative, with regard to the fifteen terms of the Dublin Core Metadata Element Set already published || [http://www.dublincore.org/documents/dcq-html/ Dublin Core]

|-
| schema.DCTERMS || a specification of all metadata terms maintained by the Dublin Core Metadata Initiative, reflecting the changes described more fully in the 2012 document "Maintenance changes to DCMI Metadata Terms" [http://dublincore.org/usage/decisions/2012/dcterms-changes/] || [http://www.dublincore.org/documents/dcq-html/ Dublin Core]
|-
|}

'''Issues need updating given new information from linked resources.'''

Notes:
* Dublin Core. This search may help: [http://www.google.co.uk/search?as_q=rel%3Dschema.*&hl=en&num=10&btnG=Google+Search&as_epq=&as_oq=&as_eq=&lr=&as_ft=i&as_filetype=&as_qdr=all&as_occt=any&as_dt=i&as_sitesearch=http%3A%2F%2Fdublincore.org&as_rights=&safe=images].
** '''examples from that search only use invisible <code><link href></code> element'''. At first glance it appears the results from the search show only uses with the invisible <code><link href></code> element which is not ideal for content relationships. Content relationships should be user visible and thus uses with <code><a href></code> are strongly preferred.
*** [http://www.ietf.org/rfc/rfc2731.txt RFC2731] defines <code>rel="schema.AC"</code> and <code>rel="schema.RC"</code> with the pattern <code>rel="schema.PREFIX"</code> as a syntax for defining namespaces for use in meta[@name], *[@rel], *[@rev] and (as per eRDF) *[@class] attributes. A link to a Dublin Core metadata schema is generally not suitable for end users, so <code><link href></code> appears to be more appropriate than <code><a href></code> for those that use Dublin Core metadata schemas.
*** The scheme proposed above provides metadata namespace declarations. As described by DCMI specifications, such indications '''cannot''' be provided w/o a suitable namespace. In order to give complete pieces of information, the correct description set must be: <code><link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"></code> (for the namespace declaration, followed by) <code><meta name="DCTERMS.<nowiki>[element]</nowiki>" content="<nowiki>[element.value]</nowiki>"></code> for related elements.
**** Note: [http://purl.org/dc/terms/ schema.DCTERMS] is conventionally related to an upgraded elements list than [http://purl.org/dc/elements/1.1/ schema.DC] and should be preferred as rel values. Both are discussed here for subject completeness)
** '''proposal to use in content currently only theoretical'''. Thus unfortunately the use of Dublin Core in user visible content like <code><a href></code> appears to be strictly theoretical. See [http://microformats.org/discuss/mail/microformats-discuss/2008-January/011445.html microformats-discuss/2008-January/011445.html] for a proposal to use Dublin Core in user visible content.
*** '''recent improvements'''. DCMI solves some trouble concerning metadata through the ''description set model''. Some of these informations cannot currently be provided in any standard ways other than DC, namely dates, validity and periodicity. Following this public bug report ([https://www.w3.org/Bugs/Public/show_bug.cgi?format=multiple&id=22520]), the correct namespace declaration for DC and DCTERMS metadata are now considered valid HTML code. We '''must''' encourage this practice both for internal usefulness and for shared practices.

* The Dublin Core document [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] is a specification for, and gives examples of, both <link rel="schema.DC" href="http://purl.org/dc/elements/1.1/"> and <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/">. Note that Dublin Core encourages the use of DCTERMS elements over DC. A list of projects which use Dublin Core metadata is maintained [http://dublincore.org/projects/ here].
* [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] also includes examples of <link rel="DCTERMS.[element]" href="">, where [element] = subject, isReferencedBy, creator, and publisher. The <link> tag is used instead of the <meta> tag whenever the content is a URL. (Note that this use is different from, but related to, <link rel="schema.DCTERMS" href="">.) Potentially, ''any'' of the 55 DCTERMS elements could be used in this way, and this could include use in HTML 5.
** As said before, HTML5 validators now allow the use of <code><link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"></code> for namespace declarations.

* According to DCMI specification linked above, as well as [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] documentation, HTML5 @rel attribute proposed values table has been updated. It now includes a subset of DCMI ''/terms/'' namespace properties, more specifically those whose value can (or must) be logically expressed by a resource, so that the "href" attribute value becomes a non-literal value surrogate referring to the resource itself.
** Elements from ''/elements/1.1/'' namespace have not been included on purpose. According to [http://wiki.dublincore.org/index.php/FAQ/DC_and_DCTERMS_Namespaces "FAQ/DC and DCTERMS Namespaces"], the old namespace is maintained for legacy purposes only and it is not as suitable for non-literal values as the ones denoted by <code><link></code> elements.

== Use with HTTP Link Header ==
You can also use any of the rel values (that are allowed for link elements) with HTTP Link Headers,

Example: returning a Javascript file with a license (since JS itself has no way to indicate a license)
<source lang=text>
Link: <http://creativecommons.org/publicdomain/zero/1.0/>; rel="license"
</source>

For multiple licenses (e.g. CC-SA and GPL), simply use multiple <code>Link:</code> headers.
<source lang=text>
Link: <http://creativecommons.org/licenses/by-sa/3.0/>; rel="license"
Link: <http://www.gnu.org/licenses/gpl.html>; rel="license"
</source>

Example: similarly, linking to a copyright statement for an image:
<source lang=text>
Link: <http://example.org/copyright.html>; rel="copyright"
</source>
or providing a brief inline copyright statement:
<source lang=text>
Link: <data:text/plain;charset=utf-8,Copyright 2013 ExampleCo, All Rights Reserved.>; rel="copyright"
</source>

== unspecified ==
Some rel values have been added to this page perhaps in one of the tables above, but no examples, nor an actual specification explicitly stating that the value(s) should be used in the HTML 'rel' attribute could be found. They are listed here in the hopes someone can discover more specific/precise URLs to examples or specifications about them (preferably both). Until such precise URLs to examples/specs are provided, the values can be treated as they are purely theoretical and thus of little interest.

A simple list here is sufficient.

== non HTML rel values ==
There are markup languages other than HTML that also have a rel attribute, often based upon the HTML rel attribute.
It is useful to document some of these other languages and their rel values for both reference purposes, and to provide background research for the possible development and re-use of these values in HTML, as [[poshformats]] or [[microformats]]

Sources:
* [[Atom]] [[RFC4287]] specification.
* See http://www.iana.org/assignments/link-relations.html for more.
* See [http://amundsen.com/media-types/maze/format/#link-relations Maze+XML]
* See [http://amundsen.com/media-types/collection/format/#link-relations Collection+JSON]
* See [http://www.opensearch.org/Specifications/OpenSearch/1.1#Url_rel_values OpenSearch]
* See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

{| border="1"
|+
! rel value !! summary (from the relevant specification where possible)) !! defining specification

|-
| self
| From http://www.ietf.org/rfc/rfc4287.txt : <blockquote>The value "self" signifies that the IRI in the value of the href attribute identifies a resource equivalent to the containing element.</blockquote>
| [[Atom]] http://www.ietf.org/rfc/rfc4287.txt

|-
| http://gdata.youtube.com/schemas/2007#in-reply-to || See http://code.google.com/apis/youtube/2.0/developers_guide_protocol_comments.html || YouTube extension to Atom

|-
| collection || Refers to a resource which represents a collection of which the current resource is a member.

When used in the Maze+XML media type, the associated URI returns the available collection of mazes.
|| Maze+XML, Collection+JSON, OpenSearch

|-
| east || Refers to a resource to the "east" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the east in the active maze.

|| Maze+XML

|-
| exit || Refers to a resource that represents the exit or end of the current client actvity or process.

When used in the Maze+XML media type, the associated URI points to the final exit resource of the active maze.

|| Maze+XML

|-
| north || Refers to a resource that is "north" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the north in the active maze.

|| Maze+XML

|-
| south || Refers to a resource that is "south" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the south in the active maze.

|| Maze+XML

|-
| [[rel-via|via]] || Identifies a resource that is the source of the information in the context. || Atom 1.0 Syndication format (RFC 4287)

|-
| west || Refers to a resource that is "west" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the west in the active maze.

|| Maze+XML

|-
| item || The target IRI points to a resource that is a member of a collection represented by the context IRI. || Collection+JSON

|-
| create-form || When included in a resource, the "create-form" link relation MAY identify a target resource that represents the form to append a new member to the link context. || See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

|-
| edit-form || When included in a resource, the "edit-form" link relation identifies a target resource that represents the form for editing associated resource. || See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

|-
| lightframe || Opens the target in a lightbox. On inclusion it provides a simple target the lightframe and loads the content in a lightbox effect || Lightbox

|-
| superbox[image] || jQuery Superbox! is a script which allows you display windows with the lightbox effect. || superbox

|-
| wp-video-lightbox || wp-video-lightbox! is a rel to anchor tag script display videos with the lightbox effect. || wp-video-lightbox

|-
| youtube || Opens the target youtube video in using the Swipebox Plugin || Swipebox

|-
| shadowbox || shadowbox is a jQuery script for images displaying with the "lightbox" effects. || shadowbox

|-
| permission || When included in a resource, the "permission" link relation MAY identify a target resource that represents the list of entities that can access or modify the resource in the link context. || See [http://cdoc.io/spec.html#permission-link-relation Collection Document Media Type Specification]

|-
| version-history
| When included on a versioned resource, this link points to a resource containing the version history for this resource.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| latest-version
| When included on a versioned resource, this link points to a resource containing the latest (e.g., current) version.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| working-copy
| When included on a versioned resource, this link points to a working copy for this resource.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| working-copy-of
| When included on a working copy, this link points to the versioned resource from which this working copy was obtained.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| predecessor-version
| When included on a versioned resource, this link points to a resource containing the predecessor version in the version history.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| successor-version
| When included on a versioned resource, this link points to a resource containing the successor version in the version history.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| ... || ... || ...

|}

== dropped ==
The following rel values were in earlier version(s) of specification(s) and it is presumed by their absence from the most recent version of the respective specification(s) that they have been deprecated or obsoleted.

In general, you {{should not}} use any dropped values.

If any such values have been superceded by standard values (see the first table on this page), then you {{must not}} use the dropped versions.

In particular:
* if a rel value was in a draft and is missing (without explanation) from the final spec, or
* if a rel value was in a previous version of and is missing (without explanation) from an update to the specification (even a draft update)

Then absent any other information or explanation, it is presumed that the group/editors working on that specification decided to explicitly drop it (either in development, or in the updated version) and thus it should be obsoleted (not re-registered).

If you wish to add them, please research why such values were omitted from latter specifications before doing so. If you do discover the reasoning, please add a short statement or link to thereof into the appropriate place in the following table.

If there is more data, e.g. a link to an email of discussion of the spec development that explains ''why'' the rel value was dropped, and it explicitly states, e.g. it was without prejudice, or merely post-poned, or perhaps expected to be spun-out into its spec (or some other explicit positive reason), then it makes to link/cite that explicit text as part of a proposal.

Sources:
* [http://www.w3.org/MarkUp/html3/ HTML3] (HTML3) / has been superceded by [http://www.w3.org/MarkUp/Wilbur/ HTML 3.2] - which itself has been superceded by [http://www.w3.org/TR/REC-html40 HTML 4.0] - which itself has been updated by [http://w3.org/TR/html401 HTML 4.01], commonly referred to as "HTML 4" in this wiki and other places.)
* [http://www.w3.org/TR/relations.html Proposed HTML 4.0 link types] (HTML4dropped) - obsoleted/superceded by the HTML 4.0 Recommendation. Any values that were in the "Proposed HTML 4.0 link types" document but didn't make it into the HTML 4.0 Recommendation were thus explicitly dropped and should be avoided.

{| border="1"
|+
! rel value !! summary !! defining specification !! why dropped

|-
|[[rel-banner|banner]]||Was used to reference another document to be used as banner for this document (i.e. a form of "include" statement).|| HTML3 ||unknown

|-
| [[rel-begin|begin]] || identifies the author-defined start of a sequence of documents of which the current document is a node.
|| HTML4dropped||unknown

|-
| [[rel-biblioentry|biblioentry]] || identifies a bibliographic entry || HTML4dropped||unknown

|-
| [[rel-bibliography|bibliography]] || identifies a bibliography || HTML4dropped||unknown

|-
| [[rel-child|child]] (obsolete/superceded) || the target document is a hierarchical child, or subdocument, of the current document|| HTML4dropped||unknown

|-
| [[rel-citation|citation]] || the target is a bibliographic citation || HTML4dropped||unknown

|-
| [[rel-collection|collection]] || the target document is an collection that contains the current document || HTML4dropped||unknown

|-
| [[rel-definition|definition]] || identifies a definition of a term || HTML4dropped||unknown

|-
| [[rel-disclaimer|disclaimer]] || identifies a hypertext link to a legal disclaimer || HTML4dropped||unknown

|-
| [[rel-editor|editor]] || identifies a hypertext link to an editor || HTML4dropped||unknown

|-
| [[rel-end|end]] || identifies the author-defined end of a sequence of documents of which the current document is a node. || HTML4dropped||unknown

|-
| [[rel-footnote|footnote]] || the anchor is a footnote marker and the target is a footnote || HTML4dropped||unknown

|-
| [[rel-navigate|navigate]] || the target document contains information such as a image map that will help users to gain a sense of how and where to found information || HTML4dropped||unknown

|-
| [[rel-origin|origin]] || synonym for <code>top</code> || HTML4dropped||unknown

|-
| [[rel-parent|parent]] (obsolete/superceded) || the target document is the hierarchical parent, or container, of the current document|| HTML4dropped||unknown

|-
| [[rel-pointer|pointer]] || the target is a pointer to the real target. This value can be used by a user agent to perform a pre-fetch of the specified target for evaluation until the real target is reached || HTML4dropped||unknown

|-
| [[rel-publisher|publisher]] || identifies a hypertext link to a publisher || HTML4dropped||unknown

|-
| [[rel-sibling|sibling]] (obsolete/superceded) || the target document is a child of a common parent, or a hierarchical peer of the current document|| HTML4dropped||unknown

|-
| [[rel-top|top]] || the target document is the logical top node of the tree (see also <code>begin</code>) || HTML4dropped||unknown

|-
| [[rel-trademark|trademark]] || identifies a hypertext link to a trademark notice || HTML4dropped||unknown

|-
| [[rel-translation|translation]] || the target is a translation to another language || HTML4dropped||unknown

|-
| [[rel-urc|urc]] || identifies a Universal Resource Citation || HTML4dropped||unknown

|-
|}

== dropped without prejudice ==
In one known instance (from HTML4 to HTML5), some rel values were in an earlier version of a specification (or a proposal) and were dropped from a latter (draft) version, and it was noted that these values were dropped with the intent that they could still be proposed in a registry and thus they explicitly were not deprecated or obsoleted. This section documents such values as separate from the [[#dropped|dropped]] section.

In general, you {{should not}} use any dropped values.

If any such values have been superceded by standard values (see the first table on this page), then you {{must not}} use the dropped versions.

Rel values that were dropped without prejudice from a specification will be considered similar to new values that have never been specified.

If you know of additional rel values that were dropped without prejudice from an update to a specification, please cite a URL and quote from the group developing the specification that officially states from that group that the dropping of the values was done without prejudice, or equivalent statement (such as explicit allowance of external registration, proposal, and/or development).

This table serves a historical purpose. If you wish to propose a value from this table, please copy it and leave it in place.

Sources:
* Several rel values were [http://www.w3.org/Bugs/Public/show_bug.cgi?id=7475#c15 explicitly dropped from HTML5]. Per: [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Issue 118 Decision] ('''emphasis''' added): <blockquote>"The final proposal argues for the removal of some relation values, to wit, it suggests removal of '''index, up, first and last'''. It was pointed out in survey comments that these relations are already registered in the IANA link relation registry. Presumably, '''these relations could also be entered in whatever other registry or registries HTML5 adopts for this purpose'''...."Next Steps..."Since the relations to be removed are already registered at the IANA link relation registry, no further action is needed to include them there. WG members are '''free to register or record these relations elsehwere''' [sic], as well."</blockquote>

{| border="1"
|+
! rel value
! summary
! defining specification
! why dropped

|-
| [[rel-first|first]]
| synonym for <code>begin</code>
| HTML4dropped - never in an official spec
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-index|index]]
| Refers to a document providing an index for the current document.
| was in [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-last|last]]
| synonym for <code>end</code>
| HTML4dropped - never in an official spec
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-up|up]]
|When the document forms part of a hierarchy, this link references the immediate parent of the current document.
| was in [http://www.w3.org/MarkUp/html3/dochead.html HTML3] - but [http://www.w3.org/TR/html401/types.html#type-links dropped in HTML4]
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
|}

See related [http://dev.w3.org/html5/spec/links.html#linkTypes HTML5: Link types] for existing HTML5 specified rel values.

== rejected ==
Some rel values have been proposed and rejected. They are listed here to make that explicit. Authors {{must not}} use rejected rel values.

Source: [[rejected-formats]].

{| border="1"
|+
! rel value !! origin / proposal !! why rejected
|-
| [[rel-logo|logo]]
| [http://relogo.org Relogo.org]
| [[rejected-formats#Logo]]
|-
|[[rel-pavatar|pavatar]] || [http://pavatar.com/ pavatar] || [[rejected-formats#Pavatar]]
|-
|}

== tools ==
See [[implementations]].

== addtional external research ==
Here are some additional historical references to the development or rel-values which may be useful when researching values, especially why specific values may have been proposed but abandoned.
* 1996-06-07 [http://www.w3.org/MarkUp/draft-ietf-html-relrev-00.txt Hypertext links in HTML] (copies: [http://ftp.ics.uci.edu/pub/ietf/html/draft-ietf-html-relrev-00.txt ftp.ics.uci.edu])
* 1996-11-13 [http://www.w3.org/Architecture/NOTE-link Describing and Linking Web Resources]
* 1997-01-23 [http://lists.gnu.org/archive/html/lynx-dev/1997-01/msg00537.html LYNX-DEV Lynx and the LINK tag]
* 1997-01-24 [http://lists.w3.org/Archives/Public/w3c-sgml-wg/1997Jan/0357.html Taxonomy list]
* 1997-03-28 [http://www.w3.org/TR/WD-htmllink-970328 W3C Working Draft: Hypertext Links and Meta Information in HTML]

=== previous attempts at documenting ===
There have been previous attempts at documenting known rel values, most of which fell out of date due to being dependent on a single author maintaining them. They're listed here purely for historical reasons, and are not sufficient to be references of their own (since they're just individual curations of other references)
* [http://fantasai.tripod.com/qref/Appendix/LinkTypes/ltdef.html Link Type Definitions Glossary] by fantasai
* ...

== related ==
{{rel-related-pages}}
* [[elemental-microformats]]
* [[existing-rev-values]]
* [[existing-class-names]]

== copyright ==

{{cc-pd-license}}

existing-rel-values

2015-03-12T17:08:22Z

Andy sky: /* HTML5 link type extensions */ Nowiki syntax on href attributes for examples of namespace declaration

<entry-title> existing rel values </entry-title>

This page contains tables of known HTML rel values from specifications, formats, proposals, brainstorms, and non-trivial [[POSH]] usage in the wild. In addition, dropped and rejected values are listed at the end for comprehensiveness.

usage: see [[rel-faq#How_is_rel_used|how is 'rel' used]]. Regarding rev, see: [[rel-faq#Should_rev_even_be_used|should 'rev' even be used]].

This page is also the official rel registry ([http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#other-link-types][http://www.w3.org/TR/html5/links.html#other-link-types]). Add new and proposed rel values to the following section:
* [[existing-rel-values#HTML5_link_type_extensions|HTML5 link type extension]]

== formats ==
These rel values are defined formats from specifications (HTML 4, microformats) are thus are recommended for general use. Alphabetically ordered by value.

Note:
* Do not add proposed rel values for HTML5 here, add them to the [[#HTML5_link_type_extensions|HTML5 link type extensions]] table.
* Do not add rel values you find in the wild to this table of rel formats, instead add them to the table in the [[existing-rel-values#POSH_usage|POSH section]].
* Do not add non-HTML rel values you find to this table of rel formats, instead add them to the table in the [[existing-rel-values#non_HTML_rel_values|non HTML rel values section]].
* Do not add rel values from obsolete/superceded proposals or drafts, instead add them to the table in the "dropped" section.

Sources:
* W3C Recommendations:
** [http://www.w3.org/TR/html401/types.html#h-6.12 HTML 4.01 section 6.12 Link types] (HTML4 Link types)
** [http://www.w3.org/TR/grddl/ Gleaning Resource Descriptions from Dialects of Languages] (GRDDL)
* [[microformats]] specifications
** [[xfn]]
** [[rel-license]]
** [[rel-nofollow]]

{| border="1"
|+
! Keyword
! Effect on <code>link</code>
! Effect on <code>a</code>, <code>area</code>
! Brief description (from the relevant specification where possible)
! Link to defining specification

|-
| [[rel-acquaintance|acquaintance]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be an acquaintance
| [[XFN]]

|-
| [[rel-alternate|alternate]]
| external resource
| external relation
| Designates substitute versions for the document in which the link occurs. When used together with the <code>lang</code> attribute, it implies a translated version of the document. When used together with the <code>media</code> attribute, it implies a version designed for a different medium (or media).
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-appendix|appendix]]
| allowed
| allowed
| Refers to a document serving as an appendix in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-bookmark|bookmark]]
| not allowed
| allowed
| Refers to a bookmark. A bookmark is a link to a key entry point within an extended document. The <code>title</code> attribute may be used, for example, to label the bookmark. Note that several bookmarks may be defined in each document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-chapter|chapter]]
| allowed
| allowed
| Refers to a document serving as a chapter in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-child|child]]
| not allowed
| external relation
| the referenced person is a child of the person represented by the current document
| [[XFN]]

|-
| [[rel-colleague|colleague]]
| not allowed
| external relation
| the referenced person is a colleague of the person represented by the current document
| [[XFN]]

|-
| [[rel-contact|contact]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be a contact
| [[XFN]]

|-
| [[rel-contents|contents]]
| allowed
| allowed
| Refers to a document serving as a table of contents. Some user agents also support the synonym ToC (from "Table of Contents").
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-copyright|copyright]]
| allowed
| allowed
| Refers to a copyright statement for the current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-co-resident|co-resident]]
| not allowed
| external relation
| the referenced person lives in the same residence as the person represented by the current document
| [[XFN]]

|-
| [[rel-co-worker|co-worker]]
| not allowed
| external relation
| the referenced person is a co-worker of the person represented by the current document
| [[XFN]]

|-
| [[rel-crush|crush]]
| not allowed
| external relation
| this person considers the referenced person to be a crush (i.e. has a crush on the referenced person)
| [[XFN]]

|-
| [[rel-date|date]]
| not allowed
| external relation
| this person considers the referenced person to be a date (i.e. is dating the referenced person)
| [[XFN]]

|-
| [[rel-friend|friend]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be a friend
| [[XFN]]

|-
| [[rel-glossary|glossary]]
| allowed
| allowed
| Refers to a document providing a list of terms and their definitions that pertain to the current document.||[http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-help|help]]
| allowed
| allowed
| Refers to a document offering help (more information, links to other sources information, etc.)
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-its-rules|its-rules]]
| allowed
| not allowed
| Refers to a document with external ITS rules.
| [http://www.w3.org/TR/its20/#selection-global-html5 Internationalization Tag Set (ITS) Version 2.0]

|-
| [[rel-kin|kin]]
| not allowed
| external relation
| the referenced person is part of the extended family of the person represented by the current document
| [[XFN]]

|-
| [[rel-license|license]]
| allowed
| allowed
| …indicates that the <nowiki>[referenced document]</nowiki> is a license for the current page.
| [[rel-license]]

|-
| [[rel-me|me]]
| external relation
| external relation
| the referenced document represents the same person as does the current document
| [[XFN]]

|-
| [[rel-met|met]]
| not allowed
| external relation
| this person has met the referenced person
| [[XFN]]

|-
| [[rel-muse|muse]]
| not allowed
| external relation
| the referenced person inspires the person represented by the current document
| [[XFN]]

|-
| [[rel-neighbor|neighbor]]
| not allowed
| external relation
| the referenced person lives nearby the person represented by the current document
| [[XFN]]

|-
| [[rel-next|next]]
| external relation
| external relation
| Refers to the next document in a linear sequence of documents. User agents may choose to preload the "next" document, to reduce the perceived load time.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-nofollow|nofollow]]
| not allowed
| external relation
| indicates that the destination of that hyperlink {{should-not}} be afforded any additional weight or ranking by user agents which perform link analysis upon web pages (e.g. search engines).
| [[rel-nofollow]]

|-
| [[rel-parent|parent]]
| not allowed
| external relation
| the referenced person is a parent of the person represented by the current document
| [[XFN]]

|-
| [[rel-prev|prev]]
| external relation
| external relation
| Refers to the previous document in an ordered series of documents. Some user agents also support the synonym "Previous".
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-previous|previous]]
| external relation
| external relation
| Synonym of <code>prev</code>
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-section|section]]
| allowed
| allowed
| Refers to a document serving as a section in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-sibling|sibling]]
| not allowed
| external relation
| the referenced person is a sibling of the person represented by the current document
| [[XFN]]

|-
| [[rel-spouse|spouse]]
| not allowed
| external relation
| the referenced person is a spouse of the person represented by the current document
| [[XFN]]

|-
| [[rel-start|start]]
| allowed
| allowed
| Refers to the first document in a collection of documents. This link type tells search engines which document is considered by the author to be the starting point of the collection.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-stylesheet|stylesheet]]
| external resource
| not allowed
| a style sheet for the current document used with the invisible <link href> element which is not ideal for content relationships. Content relationships should be user visible and thus uses with <a href> are strongly preferred. Unfortunately the use of stylesheet in user visible content like <a href> appears to be strictly theoretical.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-subsection|subsection]]
| allowed
| allowed
| Refers to a document serving as a subsection in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-sweetheart|sweetheart]]
| not allowed
| external relation
| this person considers the referenced person to be their sweetheart
| [[XFN]]

|-
| [[rel-tag|tag]]
| not allowed
| allowed
| …indicates that the <nowiki>[referenced document]</nowiki> is an author-designated "tag" (or keyword/subject) for the current page.
| [[rel-tag]]

|-
| [[rel-toc|toc]]
| allowed
| allowed
| Synonym of <code>contents</code> (from "Table Of Contents")
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-transformation|transformation]]
| allowed
| allowed
| Relates a source document to a transformation, usually represented in XSLT, that relates the source document syntax to the RDF graph syntax. Used in [[grddl|GRDDL]]
| [http://www.w3.org/TR/grddl/#transformation GRDDL]

|}

=== notes ===
*<code>rel="alternate"</code> can take further meaning from additional attributes, such as
** <code>rel="alternate" lang="fr"</code> (French language version of this page)
** <code>rel="alternate" media="print"</code> (printable version of this page)
** <code>rel="alternate" media="handheld"</code> (version of the page intended or better for handheld/portable devices like PDAs, cell phones, etc.)

*Synonyms such as "previous", "toc" are not as widely supported as the main term.

== proposals ==
A few rel values have been developed as drafts as a result of going through most of the microformats [[process]], and are thus listed here for your serious consideration. You may use these values, and if you find any problems with them please point them out on the respective "issues" page for the rel value.

{| border="1"
|+
! rel value !! summary !! proposed in !! external spec (if any)
|-
| [[rel-pronunciation|pronunciation]] || …indicates that the destination of the 'link' element is a document providing a pronunciation lexicon for speech-synthesis purposes. || [[rel-pronunciation]]
|-
| [[rel-directory|directory]] || …indicates that the destination of the hyperlink is a directory listing containing an entry for the current page. || [[rel-directory]]
|-
| [[rel-enclosure|enclosure]] || …indicates that the destination of that hyperlink is intended to be downloaded and cached. || [[rel-enclosure]] || [http://www.apps.ietf.org/rfc/rfc4287.html RFC4287]
|-
| [[rel-home|home]] || …indicates that the <nowiki>[referenced document]</nowiki> is the homepage of the site in which the current page appears. || [[rel-home]]
|-
| [[rel-payment|payment]] || …indicates that the destination of the hyperlink provides a way to show or give support (e.g. financial) for the current page|| [[rel-payment]]
|}

== HTML5 link type extensions ==

The following values are registered as link type extensions per the [http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#other-link-types requirements in the WHATWG HTML spec] and the [http://dev.w3.org/html5/spec/links.html#other-link-types requirements in the W3C HTML5 spec].

Before you register a new value:
* '''Please check the [[#formats|Formats table]] and DO NOT re-register''' rel values that are already there. Please note that the W3C HTML WG has made a [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Decision] to drop <code>index</code>, <code>up</code>, <code>first</code> and <code>last</code> from the HTML5 spec itself.
* '''Please check the [[#dropped|Dropped table]] and DO NOT register''' values that are already there. If you believe a rel value was dropped from another specification without prejudice, please provide link/cite to explicit text/decision stating as such, e.g. the value was merely postponed, or perhaps expected to be spun-out into its own spec from the group developing that specification.

Note that entries in the [[#formats|Formats table]] and entries that are already in HTML5 as built-in keywords are also considered extensions with the "Ratified" status.

Please make sure that registrations added here have all the required data filled in ''including'':
* "Effect on link"
* "Effect on a and area" and
* a link to a spec that documents the keyword ''as an HTML <code>rel</code> keyword''. (A spec that merely defines the file format of the link target but does not define the <code>rel</code> keyword for use in HTML is not the kind of spec that is being required here.)

Entries lacking any of the above required data will likely be removed.

Changes to this registry will not be reflected in validators in real time. But validators will typically get automatically updated with the changes within one week or so

{| border="1"
|+
! Keyword
! Effect on <code>link</code>
! Effect on <code>a</code>, <code>area</code>
! Brief description
! Link to specification
! Synonyms
! Status

|-
| [[rel-apple-touch-icon|apple-touch-icon]]
| External Resource
| Not allowed
| Specify a Webpage Icon for a “Web Clip”, or “touch icon”, for mobile devices (not limited to Apple devices).
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| probably redundant with rel=icon
| proposed

|-
| [[rel-apple-touch-icon-precomposed|apple-touch-icon-precomposed]]
| External Resource
| Not allowed
| Specify a Webpage Icon for a “Web Clip”, or “touch icon”, for mobile devices (not limited to Apple devices).
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| probably redundant with rel=icon
| proposed

|-
| [[rel-apple-touch-startup-image|apple-touch-startup-image]]
| External Resource
| Not allowed
| Specify a splashscreen for Web apps on iOS Safari
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| maybe redundant with rel=icon with the sizes attribute?
| proposed

|-
| [[rel-attachment|attachment]]
| Hyperlink
| Hyperlink
| The resource linked to is "attached" to this document, similar to email attachments. Used in WordPress.
| No formal specification
|
| proposed

|-
| [[WPVL_PRETTYPHOTO_REL]]
| Hyperlink
| Hyperlink
| Open lightbox with video
| No formal specification
|
| proposed

|-
| [[rel-authorization_endpoint|authorization_endpoint]]
| External Resource
| Not allowed
| Specify a hosted authorization server
| [http://indiewebcamp.com/distributed-indieauth distributed IndieAuth documentation]
|
| proposed

|-
| [[rel-canonical|canonical]]
| External Resource
| Not allowed
| Specifies the canonical URL for the current document in order to help avoid duplicate content.
| [http://en.wikipedia.org/wiki/Canonical_meta_tag Canonical meta tag] [http://www.Google.com/support/webmasters/bin/answer.py?answer=139066#2 Canonicalization at Google Webmaster Central] [http://www.Bing.com/community/site_blogs/b/webmaster/archive/2009/02/12/partnering-to-help-solve-duplicate-content-issues.aspx Microsoft Webmaster Center] [http://www.YSearchBlog.com/2009/02/12/fighting-duplication-adding-more-arrows-to-your-quiver/ Yahoo! Search Blog]
|
| proposed

|-
| [[rel-category|category]]
| Hyperlink
| Hyperlink
| Refers to a category assigned to the current document or post. Implemented by WordPress for indicating a relation between a blog post and a category.
| [[rel-category]]
|
| proposed

|-
| [[rel-component|component]]
| External Resource
| Not allowed
| Specify an HTML document that is treated as a component of this document.
| [https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/components/index.html Web Components]
|
| proposed

|-
| [[rel-chrome-webstore-item|chrome-webstore-item]]
| External Resource
| Not allowed
| Link tag to declare for app and extensions inline installations hosted in the Chrome Web Store.
| [https://developers.google.com/chrome/web-store/docs/inline_installation Using Inline Installation]
|
| proposed

|-
| [[rel-dcterms.(property)#conformsTo|DCTERMS.conformsTo]]
| External Resource
| Not allowed
| An established standard to which the described resource conforms. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.conformsTo" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#contributor|DCTERMS.contributor]]
| External Resource
| Not allowed
| An entity responsible for making contributions to the resource. Examples include a person, an organization, or a service. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.contributor" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#creator|DCTERMS.creator]]
| External Resource
| Not allowed
| An entity primarily responsible for making the resource. Examples include a person, an organization, or a service. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.creator" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#description|DCTERMS.description]]
| External Resource
| Not allowed
| An account of the resource. Description may include but is not limited to: an abstract, a table of contents, a graphical representation, or a free-text account of the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.description" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#hasFormat|DCTERMS.hasFormat]]
| External Resource
| Not allowed
| A related resource that is substantially the same as the pre-existing described resource, but in another format. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#hasPart|DCTERMS.hasPart]]
| External Resource
| Not allowed
| A related resource that is included either physically or logically in the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#hasVersion|DCTERMS.hasVersion]]
| External Resource
| Not allowed
| A related resource that is a version, edition, or adaptation of the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#identifier|DCTERMS.identifier]]
| External Resource
| Not allowed
| An unambiguous reference to the resource within a given context. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.identifier" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#isFormatOf|DCTERMS.isFormatOf]]
| External Resource
| Not allowed
| A related resource that is substantially the same as the described resource, but in another format. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isPartOf|DCTERMS.isPartOf]]
| External Resource
| Not allowed
| A related resource in which the described resource is physically or logically included. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isReferencedBy|DCTERMS.isReferencedBy]]
| External Resource
| Not allowed
| A related resource that references, cites, or otherwise points to the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isReplacedBy|DCTERMS.isReplacedBy]]
| External Resource
| Not allowed
| A related resource that supplants, displaces, or supersedes the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isRequiredBy|DCTERMS.isRequiredBy]]
| External Resource
| Not allowed
| A related resource that requires the described resource to support its function, delivery, or coherence. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isVersionOf|DCTERMS.isVersionOf]]
| External Resource
| Not allowed
| A related resource of which the described resource is a version, edition, or adaptation. Changes in version imply substantive changes in content rather than differences in format. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#license|DCTERMS.license]]
| External Resource
| Not allowed
| A legal document giving official permission to do something with the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.license" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#mediator|DCTERMS.mediator]]
| External Resource
| Not allowed
| An entity that mediates access to the resource and for whom the resource is intended or useful. In an educational context, a mediator might be a parent, teacher, teaching assistant, or care-giver. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.mediator" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#publisher|DCTERMS.publisher]]
| External Resource
| Not allowed
| An entity responsible for making the resource available. Examples include a person, an organization, or a service. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.publisher" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#references|DCTERMS.references]]
| External Resource
| Not allowed
| A related resource that is referenced, cited, or otherwise pointed to by the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#relation|DCTERMS.relation]]
| External Resource
| Not allowed
| A related resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#replaces|DCTERMS.replaces]]
| External Resource
| Not allowed
| A related resource that is supplanted, displaced, or superseded by the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#requires|DCTERMS.requires]]
| External Resource
| Not allowed
| A related resource that is required by the described resource to support its function, delivery, or coherence. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#rightsHolder|DCTERMS.rightsHolder]]
| External Resource
| Not allowed
| A person or organization owning or managing rights over the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.rightsHolder" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#source|DCTERMS.source]]
| External Resource
| Not allowed
| A related resource from which the described resource is derived. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#subject|DCTERMS.subject]]
| External Resource
| Not allowed
| The topic of the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="<nowiki>http://purl.org/dc/terms/</nowiki>" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-disclosure|disclosure]]
| Not allowed
| External Resource
| The 'disclosure' Link Relation Type designates a list of patent disclosures or a particular patent disclosure itself made with respect to material for which such relation type is specified.
| [http://tools.ietf.org/html/draft-yevstifeyev-disclosure-relation The 'disclosure' Link Relation Type]
|
| proposed

|-
| [[rel-discussion|discussion]]
| Hyperlink
| Hyperlink
| Refers to discussion of the current document or post.
| [[rel-discussion]]
|
| proposed

|-
| [[rel-dns-prefetch|dns-prefetch]]
| External Resource
| Not allowed
| Tells the browser to perform dns lookup for host names ahead of use.
| [https://developer.mozilla.org/En/Controlling_DNS_prefetching Mozilla documentation] [http://dev.chromium.org/developers/design-documents/dns-prefetching Google documentation]
|
| proposed

|-
| [[rel-edit|edit]]
| Hyperlink
| Not allowed
| Tells the browser where the current page can be edited
| [http://universaleditbutton.org/Registered_MIME_type#Alternate_Linking_Scheme Universal Edit Button Alternate Linking Scheme]. Implemented in at least [http://mediawiki.org MediaWiki].
|
| proposed

|-
| [[rel-edituri|EditURI]]
| External Resource
| Not allowed
| A blogging auto discovery value, commonly used by WordPress
| [http://bitworking.org/projects/atom/draft-gregorio-09.html#Edit AtomAPI]
|
| proposed

|-
| [[rel-enclosure|enclosure]]
| External Resource
| External Resource
| Indicates that the referred resource is intended to be downloaded and cached.
| [[rel-enclosure]]
|
| proposed

|-
| [[rel-entry-content|entry-content]]
| Not allowed
| External Resource
| Indicates that the referenced document is an alternative display source for an Internet Explorer Web Slice.
| [http://msdn.microsoft.com/en-us/library/cc304073(VS.85).aspx#_alternative Web Slice format specification 0.9]
|
| proposed

|-
| [[rel-external|external]]
| Not allowed
| Hyperlink
| Indicates that the referenced document is not part of the same site as the current document.
| [[rel-external]]
|
| proposed

|-
| [[rel-home|home]]
| Hyperlink
| Hyperlink
| Refers to the top level document for the current document. It can be combined with 'alternate' to indicate a feed for the site of the current page.
| [[rel-home]]
|
| proposed

|-
| [[rel-hub|hub]]
| Hyperlink
| Hyperlink
| Refers to a hub that enables registration for notification of updates to the current page.
| [http://pubsubhubbub.googlecode.com/svn/trunk/pubsubhubbub-core-0.3.html#discovery PubSubHubbub Spec]
|
| proposed

|-
| [[rel-in-reply-to|in-reply-to]]
| Hyperlink
| Hyperlink
| Refers to an original post that the current page is a comment on or reply to.
| [[rel-in-reply-to]]
|
| proposed

|-
| [[rel-index|index]]
| Hyperlink
| Hyperlink
| Refers to a document providing a list of topics with pointers that pertain to the current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
|
| proposed

|-
| [[rel-indieauth|indieauth]]
| External Resource
| Not allowed
| the IndieAuth server for the relying party to contact for IndieAuth authentication
| [http://spec.indieauth.com/ IndieAuth specification]
|
| proposed

|-
| [[rel-issues|issues]]
| Hyperlink
| Hyperlink
| Refers to issues regarding the current document or specification.
| [[rel-discussion]]
|
| proposed

|-
| [[rel-lightbox|lightbox]]
| Not allowed
| Img Pop-Up
| Images with this attribute are displayed in a larger way than embedded in a website (or how you specified it) when clicked (e.g. with installed "Lightbox 2"-Plugin). When adding [group] to rel="lightbox" all images get a clickable button for next/prev; insert into <code><a rel="lightbox[group]"><img src="http:example.com/img.jpg"></a></code>
| [http://lokeshdhakar.com/projects/lightbox2/ Lightbox 2] (needs actual specification to be kept in this list, this link is just documentation of one implementation)
|
| proposed

|-
| [[rel-manifest|manifest]]
| External Resource
| Not allowed
| Imports or links to a manifest
| [http://w3c.github.io/manifest/#linking W3C Manifest for web application]
|
| proposed

|-
| [[rel-meta|meta]]
| External Resource
| Not allowed
| External metadata about the HTML document
| [http://www.w3.org/TR/2004/REC-rdf-syntax-grammar-20040210/#section-rdf-in-HTML W3C's RDF/XML Syntax Specification]
|
| proposed

|-
| [[rel-indieauth|micropub]]
| External Resource
| Not allowed
| the micropub endpoint for creating new posts
| [http://indiewebcamp.com/micropub Micropub scecification]
|
| proposed

|-
| [[rel-openid.delegate|openid.delegate]]
| External Resource
| Not allowed
| When the page that contains the link is used as an OpenID indentifier, the relying party perform sOpenID 1.1 authentication with the link target as the identifier instead.
| [http://openid.net/specs/openid-authentication-1_1.html#delegating_authentication OpenID Authentication 1.1]
|
| proposed

|-
| [[rel-openid.server|openid.server]]
| External Resource
| Not allowed
| The OpenID server for the relying party to contact for OpenID 1.1 authentication
| [http://openid.net/specs/openid-authentication-1_1.html#anchor4 OpenID Authentication 1.1]
|
| proposed

|-
| [[rel-openid2.local_id|openid2.local_id]]
| External Resource
| Not allowed
| When the page that contains the link is used as an OpenID indentifier, the relying party perform sOpenID 2.0 authentication with the link target as the identifier instead.
| [http://openid.net/specs/openid-authentication-2_0.html#rfc.section.7.3.3 OpenID Authentication 2.0]
|
| proposed

|-
| [[rel-openid2.provider|openid2.provider]]
| External Resource
| Not allowed
| The OpenID server for the relying party to contact for OpenID 2.0 authentication
| [http://openid.net/specs/openid-authentication-2_0.html#rfc.section.7.3.3 OpenID Authentication 2.0]
|
| proposed

|-
| [[rel-p3pv1|p3pv1]]
| External Resource
| Not allowed
| References a machine-readable privacy policy description in the P3P format
| [http://www.w3.org/TR/P3P/#syntax_link P3P spec]
|
| proposed

|-
| [[rel-pgpkey|pgpkey]]
| External Resource
| Not allowed
| Associates a PGP key with a Web page so that the Web page URL can be used as the commenter's URL in PGP-signed blog comments and the blogging system receiving the comment can fetch the key and verify the signature as belonging to the owner of the URL.
| [http://golem.ph.utexas.edu/~distler/blog/archives/000320.html PGP-Signed Comments]
|
| proposed

|-
| [[rel-pingback|pingback]]
| External Resource
| Not allowed
| gives the address of the pingback server that handles pingbacks to the current document
| [http://www.hixie.ch/specs/pingback/pingback Pingback]
|
| proposed

|-
| [[rel-prerender|prerender]]
| External Resource
| External Resource
| Prerenders the Web page targeted by the link including running it scripts.
| [[rel-prerender]]
|
| proposed

|-
| [[rel-profile|profile]]
| External Resource
| Contextual External Resource
| indicate[s] that the destination of that hyperlink is a metadata profile (e.g. an [[XMDP]] profile) for the current page or portion thereof. See also [[xmdp-brainstorming]].
| [http://microformats.org/wiki/rel-profile rel-profile]
|
| proposed

|-
| [[rel-publisher|publisher]]
| External Resource
| External Resource
| Indicates that the referenced document is a metadata profile (e.g., a social-media/real-name profile such as a Google+ profile) for the publisher of the current page, or some portion of the current page.
| [https://support.google.com/plus/answer/1713826?hl=en Google help page]
|
| proposed

|-
| [[rel-rendition|rendition]]
| External Resource
| External Resource
| Indicates some example rendering, interpretation, or depiction of the source. User agents may choose to execute, display, or render the target in-place; or navigate to the target.
| [http://www.globalmentor.com/specs/html-rel-rendition/ HTML rel rendition]
|
| proposed

|-
| [[rel-reply-to|reply-to]]
| External Resource
| Hyperlink
| indicates any mailbox(es) (i.e. email addresses) to which responses are to be sent. ''Note: this is distinct from the 'in-reply-to' value which refers to the originating document, not to the address where comments should be sent.
| [http://tools.ietf.org/html/rfc2822 RFC2822] (originally [http://tools.ietf.org/html/rfc822#section-4.4.3 RFC822])
|
| ratified

|-
| [[rel-service|service]]
| External Resource
| Not allowed
| Atom Publishing Protocol editing service autodiscovery.
| [http://wiki.whatwg.org/wiki/ServiceRelExtension Documentation on the WHATWG wiki]
|
| proposed

|-
| [[rel-shortlink|shortlink]]
| External Resource
| Not allowed
| Specifies the preferred shortened URL for the page.
| [http://code.google.com/p/shortlink/wiki/Specification shortlink spec]
|
| proposed

|-
| [[rel-sidebar|sidebar]]
| Hyperlink
| Hyperlink
| Indicates that the referenced document is intended to be shown in a secondary browsing context.
| [[rel-sidebar]]
|
| proposed

|-
| [[rel-sitemap|sitemap]]
| External Resource
| Not allowed
| Provides a link to an XML document describing the layout of the site.
| [[rel-sitemap]]
|
| proposed

|-
| [[rel-subresource|subresource]]
| External Resource
| Not allowed
| An external resource intended for use within the current page.
| [http://www.chromium.org/spdy/link-headers-and-server-hint/link-rel-subresource Chromium documentation]
|
| proposed

|-
| [[rel-syndication|syndication]]
| Hyperlink
| Hyperlink
| Refers to a page which is a syndicated copy of the current page.
| [[rel-syndication]]
|
| proposed

|-
| [[rel-timesheet|timesheet]]
| External Resource
| Not allowed
| Applies a timesheet to the document.
| [http://www.w3.org/TR/timesheets/#smilTimesheetsNS-Elements-Timesheet non-normative section in the Timesheet spec]
|
| proposed

|-
| [[rel-token_endpoint|token_endpoint]]
| External Resource
| Not allowed
| Specify an HTTP endpoint that micropub clients can use to obtain an access token given an authorization code
| [http://indiewebcamp.com/token-endpoint token endpoint documentation]
|
| proposed

|-
| [[rel-webmention|webmention]]
| External Resource
| Hyperlink
| gives the address of the webmention endpoint that handles webmentions to the current document
| [http://webmention.org/ WebMention specification]
|
| proposed

|-
| [[rel-widget|widget]]
| External Resource
| External Resource
| Autodiscovery for W3C widgets
| [http://dev.w3.org/2006/waf/widgets/Overview.html#linking-to-a-widget-package-from-a-html- non-normative section in the Widget packaging spec]
|
| proposed

|-
| [[rel-wlwmanifest|wlwmanifest]]
| External Resource
| Not allowed
| Windows Live Writer manifest autodiscovery
| [http://msdn.microsoft.com/en-us/library/bb463263.aspx documentation on MSDN]
|
| proposed

|-
| [[rel-image_src|image_src]]
| External Resource
| Not allowed
| Specify a Webpage Icon for use by Facebook, Yahoo, Digg, etc.
| Unknown, but see for instance [http://www.niallkennedy.com/blog/2009/03/enhanced-social-share.html this]
| probably redundant with rel=icon
| proposed

|-
| [[rel-cmis-acl|http://docs.oasis-open.org/ns/cmis/link/200908/acl]]
| External Resource
| External Resource
| Identifies the resource containing a CMIS ACL document for the link context
| [http://docs.oasis-open.org/cmis/CMIS/v1.0/cs01/cmis-spec-v1.0.html#_Toc243905525 CMIS 1.0, Section 3.4.3.4]
|
| proposed

|-
| [[rel-stylesheet/less|stylesheet/less]]
| External Resource
| Not allowed
| Less CSS framework stylesheets.
| [http://lesscss.org/#-client-side-usage Less CSS usage]
|
| proposed

|}

== brainstorming ==
Several rel values are being brainstormed as potential microformats and are thus listed here. If you find you have a use for such semantics in real world examples, consider trying out these values and provide feedback on the respective brainstorming page(s) with your results and experiences.

You may list new proposed rel values here, and even better if you can list and link to POSH uses in the wild.

{| border="1"
|+
! rel value !! summary !! brainstormed in and usage in the wild

|-
| [[rel-accessibility|accessibility]] || indicate[s] that the destination of that hyperlink contains accessibility information for the current page. || [http://www.brucelawson.co.uk/2009/rel-accessibility/ blog post] which itself uses the rel value in a <link> tag in the head of the document.

|-
| [[rel-author|author]] || indicate[s] that the destination of that hyperlink represents the author of the current page. Combines with [[rel-me|rel-me]] to chain authorship information. || Google has said it will index rel-Author in this [http://googlewebmastercentral.blogspot.com/2011/06/authorship-markup-and-web-search.html blog post], with further [http://www.google.com/support/webmasters/bin/answer.py?answer=1229920 discussion of the rel-me connection] See also [http://dev.w3.org/html5/spec/Overview.html#link-type-author the HTML5 spec]

|-
| [[rel-bibliography|bibliography]] || indicate[s] that the destination of that hyperlink is a bibliography for the current page. || [http://microformats.org/discuss/mail/microformats-discuss/2007-October/010863.html mailing list post, 2007-10-15]

|-
| [[rel-cite|cite]] || indicate[s] that the destination of that hyperlink is an authoritative source or a precedent to the current page. || [[distributed-conversation-brainstorming]]

|-
| [[rel-group|group]] || the referenced document represents a group to which the person represented by the current document belongs || [[group-brainstorming]]

|-
| [[rel-jslicense|jslicense]]
| Refers to a document with JavaScript source code and license information (also called a [http://www.gnu.org/licenses/javascript-labels.html JavaScript License Web Labels] page). We might want choose a keyword for this that is more general -- there are many situations besides JavaScript in which it is desirable or required by license agreements (e.g., GNU GPL) to make an offer of both the source code and a copy of a license when distributing object code versions of a given work.
|* Brainstorming page -- thoughts on the name?
* Ex. [http://www.eff.org EFF.org] (on <code>link</code>)
* Ex. [http://www.fsf.org FSF.org] (on <code>a</code>)
|-
| [[rel-longdesc|longdesc]] || Alternative to the img longdesc attribute, for use on visible links || [http://www.google.com/search?q=rel%3D%22longdesc%22 Google search for rel=longdesc in the wild] shows many sources of proposals. Please edit this to list the earliest and perhaps most recent/comprehensive proposal. No known real world POSH usage in the wild yet.

|-
| [[rel-map|map]] || Link to a map. Possibly embedded within an adr, hCard, geo or hCalendar. Parsers {{may}} attempt to parse the URL if it is a link to a known map site (e.g. Geohash, Google Maps, Multimap) and extract co-ordinates and other useful data. || (to [[User:TobyInk|TobyInk]] by email)

|-
| [[rel-member|member]] || the referenced document represents a member of the group represented by the current document || [[group-brainstorming]]

|-
| [[rel-m_PageScroll2id|m_PageScroll2id]] || JS to scroll to a defined ID || [[group-brainstorming]]

|-
| [[rel-preconnect|preconnect]] || indicates an origin that will be used to fetch required resources. Initiating an early connection, which includes the DNS lookup, TCP handshake, and optional TLS negotiation, allows the user agent to mask the high costs of connection establishment latency.|| [https://igrigorik.github.io/resource-hints/#preconnect resource hints draft]

|-
| [[rel-prefetch|prefetch]] || indicates the URL and content-type of a resource that is likely to be a required resource when the next action or navigation is triggered. Initiating an early fetch allows the user agent to mask the request latency of the resource and make it available sooner to the application.|| [https://igrigorik.github.io/resource-hints/#prefetch resource hints draft]

|-
| [[rel-preload|preload]] || indicates the URL and content-type of a resource that should be fetched as early as possible by the user agent. Initiating an early fetch allows the user agent to mask the request latency of the resource and make it available sooner to the application.|| [https://igrigorik.github.io/resource-hints/#preload resource hints draft]

|-
| [[rel-prerender|prerender]] || indicates the URL of the next navigation target. Initiating a prerender allows the user agent to deliver an instant navigation experience: the user agent downloads the top-level resource and its assets, and performs all of the processing steps required to show the page without actually showing it to the user.|| [https://igrigorik.github.io/resource-hints/#prerender resource hints draft]

|-
| [[rel-profile|profile]] || indicate[s] that the destination of that hyperlink is a metadata profile (e.g. an [[XMDP]] profile) for the current page or portion thereof || [[xmdp-brainstorming]]

|-
| [[rel-shortlink|shortlink]] || the referenced document represents the current document but with a shorter URL || [http://samj.net/2009/04/introducing-relshort-better-alternative.html blog post]
|-
| source || the referenced document represents the source code for the current document or project || [[source-brainstorming]] [http://adactio.com/journal/6667/ blog post]

|-
| vcalendar-parent || link from an event to a containing event || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]
|-
| vcalendar-child || link from an event to a contained event || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]
|-
| vcalendar-sibling || link from an event to a related event with the same container || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]

|-
| [[rel-status|status]] || the referenced document represents the status (or source of status updates) for the author of this document || [http://monkinetic.com/2009/11/24/status-autodiscovery-relstatus.html blog post]

|}

=== more brainstorming ===
See also:
* [[genealogy-brainstorming]] for some thoughts on possible additional values for family relationships (use existing [[XFN]] [[rel-parent|parent]], [[rel-child|child]], [[rel-sibling|sibling]], [[rel-spouse|spouse]], [[rel-kin|kin]] values first though)
* [[xpn-brainstorming]] for some thoughts on possible additional values for professional relationships (use existing [[XFN]] [[rel-co-worker|co-worker]], [[rel-colleague|colleague]] values first though)

== POSH usage ==
There are numerous rel values used as [[POSH]], both in the wild, whose origins are not necessarily known, nor are their meanings consistent. There are also numerous rel values from external proposals of varying degrees of merit. It is useful to document their existence and summarize their implied meanings/usage intent as research that may be used to perhaps take one or more of them thru the microformats [[process]] if there is both sufficient interest and sufficient in the wild usage.

Note: If a value is missing from this table, it may have either already been promoted by writing it up as a proposal, or demoted by being explicitly dropped. Please check the other tables first before adding to this table.

Note: this list is incomplete, please help complete it from the following sources:

External sources:
* [http://developer.mozilla.org/about/meta Meta Information in DevMo Docs] (DevMo)
* [http://wiki.mozilla.org/Microsummaries Microsummary]
* [http://lachy.id.au/dev/markup/specs/wclr/ Web Communication Link Relationships] (WCLR)
* [http://www.w3.org/MarkUp/Relationships.html W3C Link Relationship values draft] (LRdraft) - from a draft of the HTML spec circa 1991.
* [http://www.whatwg.org/specs/web-apps/current-work/multipage/section-links.html#linkTypes HTML5 draft] '''Liable to change'''
* [http://wiki.foaf-project.org/Autodiscovery FOAF Project Wiki: Autodiscovery] (FOAF)
* [http://www.apps.ietf.org/rfc/rfc4685.html RFC4685]
* [http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html Google Blog]

{| border="1"
|+
! rel value !! summary !! origin !! proposal(s)

|-
| [[rel-archive|archive]] || index of archived entries || unknown, perhaps Wordpress open source blogging software || WCLR

|-
| [[rel-archives|archives]] || Provides a link to a collection of records, documents, or other materials of historical interest. || || HTML5

|-
|[[rel-author|author]]||see brainstorming above for suggested use by google||unknown || DevMo / HTML5

|-
| [[rel-canonical|canonical]] || To help search engines disambiguate the same page with multiple representations || Google || [http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html Google]/[http://www.bing.com/community/blogs/webmaster/archive/2009/02/12/partnering-to-help-solve-duplicate-content-issues.aspx Microsoft]/[http://www.ysearchblog.com/2009/02/12/fighting-duplication-adding-more-arrows-to-your-quiver/ Yahoo!], [http://blog.ask.com/2009/02/ask-is-going-canonical.html Ask Jeeves]

|-
| [[rel-comment|comment]] || … || … || WCLR

|-
| [[rel-contribution|contribution]] || … || … || WCLR

|-
| [[rel-edituri|EditURI]]
| Location of the xml-rpc gateway for a Wordpress install that allows external programs to add, edit and delete posts. Used by "[http://codex.wordpress.org/Weblog_Client WordPress blog client]" software for automating posting and updating blog content from your desktop. || Seen in [http://www.wordpress.org/ WordPress], e.g. [http://www.tom-watson.co.uk/]. || Description stubbed in [[rel-edituri]].

|-
| [[rel-endorsed|endorsed]] || … || … || WCLR

|-
| [[rel-fan|fan]] || xxxx. || … || [[hcard-user-profile-authoring]]

|-
| [[rel-feed|feed]] || Gives the address of a syndication feed for the current document. || … || WCLR/ HTML5

|-
| [[rel-footnote|footnote]] || Location of the footnote on a link to a footnote. || Markdown preprocessors such as [http://maruku.rubyforge.org/ Maruku] || HTML5

|-
| [[rel-icon|icon]] || Imports an icon to represent the current document. (Allowed in <code>link</code> only) || [http://dev.w3.org/html5/spec-LC/links.html#rel-icon HTML5] || WCLR/HTML5

|-
| [[rel-kinetic-stylesheet|kinetic-stylesheet]] || Imports a [http://kssproject.org/ KSS] 'kinetic stylesheet' to bind dynamic behavior to elements || Used in the [http://plone.org Plone] Content Management System || …

|-
| [[rel-lightbox|lightbox]] || Hook - Indicates that following the link will trigger a "lightbox" script (Allowed in <code>link</code> only) || ([http://www.google.co.uk/search?q=rel%3D%22lightbox%22 Google search for rel=lightbox in the wild]) || …

|-
| [[rel-lightbox|lightbox[group_name]]] || Used by lightbox scripts to group different sets of images together. Images from one group will not appear in another group's lightbox. See also "lightbox". || [http://lokeshdhakar.com/projects/lightbox2/#how Lightbox 2] || …

|-
| [[rel-prettyPhoto|prettyPhoto]] || See also "lightbox" || ([http://www.google.fr/search?q=rel%3D%22prettyphoto%22 Google search for rel="prettyphoto" in the wild]) || …

|-
| [[rel-clearbox|clearbox]] || See also "lightbox" || ([http://www.google.fr/search?q=rel%3D%22clearbox%22 Google search for rel="clearbox" in the wild]) || …

|-
| [[rel-made|made]] || … || … || LRdraft

|-
| [[rel-meta|meta]] || … || [http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/#transport 1999 W3C RDF syntax REC] || FOAF

|-
| [[rel-microsummary|microsummary]]|| … || … ||[http://wiki.mozilla.org/Microsummaries Microsummary], be aware of: [[page-summary-formats#Issues_2|microsummary issues]]

|-
| [[rel-noreferrer|noreferrer]] || indicates that no referrer information is to be leaked when following the link. || [http://dev.w3.org/html5/spec-LC/links.html#rel-noreferrer HTML5] || HTML5

|-
| [[rel-openid-delegate|openid.delegate]] || … || ([http://www.google.co.uk/search?q=%22rel%3Dopenid%22 Google search for rel=openid.* in the wild]) || …

|-
| [[rel-openid-server|openid.server]] || … || ([http://www.google.co.uk/search?q=%22rel%3Dopenid%22 Google search for rel=openid.* in the wild]) || …

|-
| [[rel-permalink|permalink]] || … || … || WCLR

|-
| [[rel-pgpkey|pgpkey]] || (see also rel-publickey) || … || [http://golem.ph.utexas.edu/~distler/blog/archives/000320.html], [http://golem.ph.utexas.edu/~distler/blog/archives/000325.html]

|-
| [[rel-pingback|pingback]] || Gives the address of the pingback server that handles pingbacks to the current document. (Allowed in <code>link</code> only) || … || WCLR/ HTML5

|-
| [[rel-popover|popover]] || Used by a JS widget to display a large, descriptive tooltip. || [http://twitter.github.com/bootstrap Twitter's Bootstrap] [http://twitter.github.com/bootstrap/javascript.html#popovers Popover.js] || …

|-
| [[rel-prefetch|prefetch]] || Specifies that the target resource should be pre-emptively cached. (Allowed in <code>link</code> only) || … || HTML5

|-
| [[rel-privacy|privacy]] || Specifies that the target resource is the privacy policy. || … || …

|-
| [[rel-publickey|publickey]] || (see also rel-pgpkey) || … || [http://rasterweb.net/raster/2002/12/12/20021212072812/]

|-
| [[rel-referral|referral]] || … || … || WCLR

|-
| [[rel-related|related]] || … || … || WCLR

|-
| [[rel-replies|replies]] || indicates a continued thread || unknown || [http://www.apps.ietf.org/rfc/rfc4685.html RFC4685]

|-
| [[rel-resource|resource]] || … || … || WCLR

|-
| [[rel-search|search]] || … || unknown || unknown

|-
| [[rel-sitemap|sitemap]] || Links to a site map document. || … || http://www.sitemaps.org/

|-
| [[rel-sponsor|sponsor]] || … || … || WCLR

|-
| [[rel-tooltip|tooltip]] || Used by a JS widget to display a tooltip similar (though more customizable) to what is shown by browsers if the 'title' attribute is present. || [http://twitter.github.com/bootstrap Twitter's Bootstrap] [http://twitter.github.com/bootstrap/javascript.html#tooltips Tooltip.js] (and likely other JS tools) || …

|-
| [[rel-trackback|trackback]] || … || unknown, perhaps open source Movable Type blogging software || WCLR

|-
| [[rel-unendorsed|unendorsed]] || (probably redundant to [[rel-nofollow|nofollow]]) || … || WCLR

|-
| [[rel-user|user]] || … || … || WCLR
|-
| [[rel-wlwmanifest|wlwmanifest]] || Used by "[http://explore.live.com/windows-live-writer Windows Live Writer]," a Microsoft [http://codex.wordpress.org/Weblog_Client blog client] for automating posting and updating blog content from your desktop. || Seen in [http://www.wordpress.org/ WordPress], e.g. [http://www.tom-watson.co.uk/]. Similar values are probably used by other blog content management systems as well. || …

|}

=== WCLR ===

The WCLR proposal is described by its author (in e-mail, 2007-09-25) as:

<blockquote>
…now effectively obsolete, since HTML5 and Microformats cover all the worthwhile relationships in that already.

These are [http://www.whatwg.org/specs/web-apps/current-work/multipage/section-links.html#linkTypes covered by HTML5 already]:

* permalink -> bookmark
* archive -> archives
* feed
* pingback
* unendorsed -> nofollow

The rest now seem unnecessary.
</blockquote>

Nonetheless, there may be some mileage in using them in microformats, at least until HTML5 is widely available.

== Dublin Core ==
In the past, Dublin Core values have been added to this page in the table about HTML5 features, but no examples, nor an actual specification explicitly stating how the value(s) should be used in HTML could be found. The linked specifications below have been updated so we should start considering Dublin Core values accordingly.

{| border="1"
|+
! rel value !! summary !! source
|-
| schema.DC || a specification of all metadata terms maintained by the Dublin Core Metadata Initiative, with regard to the fifteen terms of the Dublin Core Metadata Element Set already published || [http://www.dublincore.org/documents/dcq-html/ Dublin Core]

|-
| schema.DCTERMS || a specification of all metadata terms maintained by the Dublin Core Metadata Initiative, reflecting the changes described more fully in the 2012 document "Maintenance changes to DCMI Metadata Terms" [http://dublincore.org/usage/decisions/2012/dcterms-changes/] || [http://www.dublincore.org/documents/dcq-html/ Dublin Core]
|-
|}

'''Issues need updating given new information from linked resources.'''

Notes:
* Dublin Core. This search may help: [http://www.google.co.uk/search?as_q=rel%3Dschema.*&hl=en&num=10&btnG=Google+Search&as_epq=&as_oq=&as_eq=&lr=&as_ft=i&as_filetype=&as_qdr=all&as_occt=any&as_dt=i&as_sitesearch=http%3A%2F%2Fdublincore.org&as_rights=&safe=images].
** '''examples from that search only use invisible <code><link href></code> element'''. At first glance it appears the results from the search show only uses with the invisible <code><link href></code> element which is not ideal for content relationships. Content relationships should be user visible and thus uses with <code><a href></code> are strongly preferred.
*** [http://www.ietf.org/rfc/rfc2731.txt RFC2731] defines <code>rel="schema.AC"</code> and <code>rel="schema.RC"</code> with the pattern <code>rel="schema.PREFIX"</code> as a syntax for defining namespaces for use in meta[@name], *[@rel], *[@rev] and (as per eRDF) *[@class] attributes. A link to a Dublin Core metadata schema is generally not suitable for end users, so <code><link href></code> appears to be more appropriate than <code><a href></code> for those that use Dublin Core metadata schemas.
*** The scheme proposed above provides metadata namespace declarations. As described by DCMI specifications, such indications '''cannot''' be provided w/o a suitable namespace. In order to give complete pieces of information, the correct description set must be: <code><link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"></code> (for the namespace declaration, followed by) <code><meta name="DCTERMS.<nowiki>[element]</nowiki>" content="<nowiki>[element.value]</nowiki>"></code> for related elements.
**** Note: [http://purl.org/dc/terms/ schema.DCTERMS] is conventionally related to an upgraded elements list than [http://purl.org/dc/elements/1.1/ schema.DC] and should be preferred as rel values. Both are discussed here for subject completeness)
** '''proposal to use in content currently only theoretical'''. Thus unfortunately the use of Dublin Core in user visible content like <code><a href></code> appears to be strictly theoretical. See [http://microformats.org/discuss/mail/microformats-discuss/2008-January/011445.html microformats-discuss/2008-January/011445.html] for a proposal to use Dublin Core in user visible content.
*** '''recent improvements'''. DCMI solves some trouble concerning metadata through the ''description set model''. Some of these informations cannot currently be provided in any standard ways other than DC, namely dates, validity and periodicity. Following this public bug report ([https://www.w3.org/Bugs/Public/show_bug.cgi?format=multiple&id=22520]), the correct namespace declaration for DC and DCTERMS metadata are now considered valid HTML code. We '''must''' encourage this practice both for internal usefulness and for shared practices.

* The Dublin Core document [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] is a specification for, and gives examples of, both <link rel="schema.DC" href="http://purl.org/dc/elements/1.1/"> and <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/">. Note that Dublin Core encourages the use of DCTERMS elements over DC. A list of projects which use Dublin Core metadata is maintained [http://dublincore.org/projects/ here].
* [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] also includes examples of <link rel="DCTERMS.[element]" href="">, where [element] = subject, isReferencedBy, creator, and publisher. The <link> tag is used instead of the <meta> tag whenever the content is a URL. (Note that this use is different from, but related to, <link rel="schema.DCTERMS" href="">.) Potentially, ''any'' of the 55 DCTERMS elements could be used in this way, and this could include use in HTML 5.
** As said before, HTML5 validators now allow the use of <code><link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"></code> for namespace declarations.

* According to DCMI specification linked above, as well as [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] documentation, HTML5 @rel attribute proposed values table has been updated. It now includes a subset of DCMI ''/terms/'' namespace properties, more specifically those whose value can (or must) be logically expressed by a resource, so that the "href" attribute value becomes a non-literal value surrogate referring to the resource itself.
** Elements from ''/elements/1.1/'' namespace have not been included on purpose. According to [http://wiki.dublincore.org/index.php/FAQ/DC_and_DCTERMS_Namespaces "FAQ/DC and DCTERMS Namespaces"], the old namespace is maintained for legacy purposes only and it is not as suitable for non-literal values as the ones denoted by <code><link></code> elements.

== Use with HTTP Link Header ==
You can also use any of the rel values (that are allowed for link elements) with HTTP Link Headers,

Example: returning a Javascript file with a license (since JS itself has no way to indicate a license)
<source lang=text>
Link: <http://creativecommons.org/publicdomain/zero/1.0/>; rel="license"
</source>

For multiple licenses (e.g. CC-SA and GPL), simply use multiple <code>Link:</code> headers.
<source lang=text>
Link: <http://creativecommons.org/licenses/by-sa/3.0/>; rel="license"
Link: <http://www.gnu.org/licenses/gpl.html>; rel="license"
</source>

Example: similarly, linking to a copyright statement for an image:
<source lang=text>
Link: <http://example.org/copyright.html>; rel="copyright"
</source>
or providing a brief inline copyright statement:
<source lang=text>
Link: <data:text/plain;charset=utf-8,Copyright 2013 ExampleCo, All Rights Reserved.>; rel="copyright"
</source>

== unspecified ==
Some rel values have been added to this page perhaps in one of the tables above, but no examples, nor an actual specification explicitly stating that the value(s) should be used in the HTML 'rel' attribute could be found. They are listed here in the hopes someone can discover more specific/precise URLs to examples or specifications about them (preferably both). Until such precise URLs to examples/specs are provided, the values can be treated as they are purely theoretical and thus of little interest.

A simple list here is sufficient.

== non HTML rel values ==
There are markup languages other than HTML that also have a rel attribute, often based upon the HTML rel attribute.
It is useful to document some of these other languages and their rel values for both reference purposes, and to provide background research for the possible development and re-use of these values in HTML, as [[poshformats]] or [[microformats]]

Sources:
* [[Atom]] [[RFC4287]] specification.
* See http://www.iana.org/assignments/link-relations.html for more.
* See [http://amundsen.com/media-types/maze/format/#link-relations Maze+XML]
* See [http://amundsen.com/media-types/collection/format/#link-relations Collection+JSON]
* See [http://www.opensearch.org/Specifications/OpenSearch/1.1#Url_rel_values OpenSearch]
* See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

{| border="1"
|+
! rel value !! summary (from the relevant specification where possible)) !! defining specification

|-
| self
| From http://www.ietf.org/rfc/rfc4287.txt : <blockquote>The value "self" signifies that the IRI in the value of the href attribute identifies a resource equivalent to the containing element.</blockquote>
| [[Atom]] http://www.ietf.org/rfc/rfc4287.txt

|-
| http://gdata.youtube.com/schemas/2007#in-reply-to || See http://code.google.com/apis/youtube/2.0/developers_guide_protocol_comments.html || YouTube extension to Atom

|-
| collection || Refers to a resource which represents a collection of which the current resource is a member.

When used in the Maze+XML media type, the associated URI returns the available collection of mazes.
|| Maze+XML, Collection+JSON, OpenSearch

|-
| east || Refers to a resource to the "east" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the east in the active maze.

|| Maze+XML

|-
| exit || Refers to a resource that represents the exit or end of the current client actvity or process.

When used in the Maze+XML media type, the associated URI points to the final exit resource of the active maze.

|| Maze+XML

|-
| north || Refers to a resource that is "north" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the north in the active maze.

|| Maze+XML

|-
| south || Refers to a resource that is "south" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the south in the active maze.

|| Maze+XML

|-
| [[rel-via|via]] || Identifies a resource that is the source of the information in the context. || Atom 1.0 Syndication format (RFC 4287)

|-
| west || Refers to a resource that is "west" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the west in the active maze.

|| Maze+XML

|-
| item || The target IRI points to a resource that is a member of a collection represented by the context IRI. || Collection+JSON

|-
| create-form || When included in a resource, the "create-form" link relation MAY identify a target resource that represents the form to append a new member to the link context. || See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

|-
| edit-form || When included in a resource, the "edit-form" link relation identifies a target resource that represents the form for editing associated resource. || See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

|-
| lightframe || Opens the target in a lightbox. On inclusion it provides a simple target the lightframe and loads the content in a lightbox effect || Lightbox

|-
| superbox[image] || jQuery Superbox! is a script which allows you display windows with the lightbox effect. || superbox

|-
| wp-video-lightbox || wp-video-lightbox! is a rel to anchor tag script display videos with the lightbox effect. || wp-video-lightbox

|-
| youtube || Opens the target youtube video in using the Swipebox Plugin || Swipebox

|-
| shadowbox || shadowbox is a jQuery script for images displaying with the "lightbox" effects. || shadowbox

|-
| permission || When included in a resource, the "permission" link relation MAY identify a target resource that represents the list of entities that can access or modify the resource in the link context. || See [http://cdoc.io/spec.html#permission-link-relation Collection Document Media Type Specification]

|-
| version-history
| When included on a versioned resource, this link points to a resource containing the version history for this resource.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| latest-version
| When included on a versioned resource, this link points to a resource containing the latest (e.g., current) version.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| working-copy
| When included on a versioned resource, this link points to a working copy for this resource.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| working-copy-of
| When included on a working copy, this link points to the versioned resource from which this working copy was obtained.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| predecessor-version
| When included on a versioned resource, this link points to a resource containing the predecessor version in the version history.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| successor-version
| When included on a versioned resource, this link points to a resource containing the successor version in the version history.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| ... || ... || ...

|}

== dropped ==
The following rel values were in earlier version(s) of specification(s) and it is presumed by their absence from the most recent version of the respective specification(s) that they have been deprecated or obsoleted.

In general, you {{should not}} use any dropped values.

If any such values have been superceded by standard values (see the first table on this page), then you {{must not}} use the dropped versions.

In particular:
* if a rel value was in a draft and is missing (without explanation) from the final spec, or
* if a rel value was in a previous version of and is missing (without explanation) from an update to the specification (even a draft update)

Then absent any other information or explanation, it is presumed that the group/editors working on that specification decided to explicitly drop it (either in development, or in the updated version) and thus it should be obsoleted (not re-registered).

If you wish to add them, please research why such values were omitted from latter specifications before doing so. If you do discover the reasoning, please add a short statement or link to thereof into the appropriate place in the following table.

If there is more data, e.g. a link to an email of discussion of the spec development that explains ''why'' the rel value was dropped, and it explicitly states, e.g. it was without prejudice, or merely post-poned, or perhaps expected to be spun-out into its spec (or some other explicit positive reason), then it makes to link/cite that explicit text as part of a proposal.

Sources:
* [http://www.w3.org/MarkUp/html3/ HTML3] (HTML3) / has been superceded by [http://www.w3.org/MarkUp/Wilbur/ HTML 3.2] - which itself has been superceded by [http://www.w3.org/TR/REC-html40 HTML 4.0] - which itself has been updated by [http://w3.org/TR/html401 HTML 4.01], commonly referred to as "HTML 4" in this wiki and other places.)
* [http://www.w3.org/TR/relations.html Proposed HTML 4.0 link types] (HTML4dropped) - obsoleted/superceded by the HTML 4.0 Recommendation. Any values that were in the "Proposed HTML 4.0 link types" document but didn't make it into the HTML 4.0 Recommendation were thus explicitly dropped and should be avoided.

{| border="1"
|+
! rel value !! summary !! defining specification !! why dropped

|-
|[[rel-banner|banner]]||Was used to reference another document to be used as banner for this document (i.e. a form of "include" statement).|| HTML3 ||unknown

|-
| [[rel-begin|begin]] || identifies the author-defined start of a sequence of documents of which the current document is a node.
|| HTML4dropped||unknown

|-
| [[rel-biblioentry|biblioentry]] || identifies a bibliographic entry || HTML4dropped||unknown

|-
| [[rel-bibliography|bibliography]] || identifies a bibliography || HTML4dropped||unknown

|-
| [[rel-child|child]] (obsolete/superceded) || the target document is a hierarchical child, or subdocument, of the current document|| HTML4dropped||unknown

|-
| [[rel-citation|citation]] || the target is a bibliographic citation || HTML4dropped||unknown

|-
| [[rel-collection|collection]] || the target document is an collection that contains the current document || HTML4dropped||unknown

|-
| [[rel-definition|definition]] || identifies a definition of a term || HTML4dropped||unknown

|-
| [[rel-disclaimer|disclaimer]] || identifies a hypertext link to a legal disclaimer || HTML4dropped||unknown

|-
| [[rel-editor|editor]] || identifies a hypertext link to an editor || HTML4dropped||unknown

|-
| [[rel-end|end]] || identifies the author-defined end of a sequence of documents of which the current document is a node. || HTML4dropped||unknown

|-
| [[rel-footnote|footnote]] || the anchor is a footnote marker and the target is a footnote || HTML4dropped||unknown

|-
| [[rel-navigate|navigate]] || the target document contains information such as a image map that will help users to gain a sense of how and where to found information || HTML4dropped||unknown

|-
| [[rel-origin|origin]] || synonym for <code>top</code> || HTML4dropped||unknown

|-
| [[rel-parent|parent]] (obsolete/superceded) || the target document is the hierarchical parent, or container, of the current document|| HTML4dropped||unknown

|-
| [[rel-pointer|pointer]] || the target is a pointer to the real target. This value can be used by a user agent to perform a pre-fetch of the specified target for evaluation until the real target is reached || HTML4dropped||unknown

|-
| [[rel-publisher|publisher]] || identifies a hypertext link to a publisher || HTML4dropped||unknown

|-
| [[rel-sibling|sibling]] (obsolete/superceded) || the target document is a child of a common parent, or a hierarchical peer of the current document|| HTML4dropped||unknown

|-
| [[rel-top|top]] || the target document is the logical top node of the tree (see also <code>begin</code>) || HTML4dropped||unknown

|-
| [[rel-trademark|trademark]] || identifies a hypertext link to a trademark notice || HTML4dropped||unknown

|-
| [[rel-translation|translation]] || the target is a translation to another language || HTML4dropped||unknown

|-
| [[rel-urc|urc]] || identifies a Universal Resource Citation || HTML4dropped||unknown

|-
|}

== dropped without prejudice ==
In one known instance (from HTML4 to HTML5), some rel values were in an earlier version of a specification (or a proposal) and were dropped from a latter (draft) version, and it was noted that these values were dropped with the intent that they could still be proposed in a registry and thus they explicitly were not deprecated or obsoleted. This section documents such values as separate from the [[#dropped|dropped]] section.

In general, you {{should not}} use any dropped values.

If any such values have been superceded by standard values (see the first table on this page), then you {{must not}} use the dropped versions.

Rel values that were dropped without prejudice from a specification will be considered similar to new values that have never been specified.

If you know of additional rel values that were dropped without prejudice from an update to a specification, please cite a URL and quote from the group developing the specification that officially states from that group that the dropping of the values was done without prejudice, or equivalent statement (such as explicit allowance of external registration, proposal, and/or development).

This table serves a historical purpose. If you wish to propose a value from this table, please copy it and leave it in place.

Sources:
* Several rel values were [http://www.w3.org/Bugs/Public/show_bug.cgi?id=7475#c15 explicitly dropped from HTML5]. Per: [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Issue 118 Decision] ('''emphasis''' added): <blockquote>"The final proposal argues for the removal of some relation values, to wit, it suggests removal of '''index, up, first and last'''. It was pointed out in survey comments that these relations are already registered in the IANA link relation registry. Presumably, '''these relations could also be entered in whatever other registry or registries HTML5 adopts for this purpose'''...."Next Steps..."Since the relations to be removed are already registered at the IANA link relation registry, no further action is needed to include them there. WG members are '''free to register or record these relations elsehwere''' [sic], as well."</blockquote>

{| border="1"
|+
! rel value
! summary
! defining specification
! why dropped

|-
| [[rel-first|first]]
| synonym for <code>begin</code>
| HTML4dropped - never in an official spec
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-index|index]]
| Refers to a document providing an index for the current document.
| was in [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-last|last]]
| synonym for <code>end</code>
| HTML4dropped - never in an official spec
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-up|up]]
|When the document forms part of a hierarchy, this link references the immediate parent of the current document.
| was in [http://www.w3.org/MarkUp/html3/dochead.html HTML3] - but [http://www.w3.org/TR/html401/types.html#type-links dropped in HTML4]
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
|}

See related [http://dev.w3.org/html5/spec/links.html#linkTypes HTML5: Link types] for existing HTML5 specified rel values.

== rejected ==
Some rel values have been proposed and rejected. They are listed here to make that explicit. Authors {{must not}} use rejected rel values.

Source: [[rejected-formats]].

{| border="1"
|+
! rel value !! origin / proposal !! why rejected
|-
| [[rel-logo|logo]]
| [http://relogo.org Relogo.org]
| [[rejected-formats#Logo]]
|-
|[[rel-pavatar|pavatar]] || [http://pavatar.com/ pavatar] || [[rejected-formats#Pavatar]]
|-
|}

== tools ==
See [[implementations]].

== addtional external research ==
Here are some additional historical references to the development or rel-values which may be useful when researching values, especially why specific values may have been proposed but abandoned.
* 1996-06-07 [http://www.w3.org/MarkUp/draft-ietf-html-relrev-00.txt Hypertext links in HTML] (copies: [http://ftp.ics.uci.edu/pub/ietf/html/draft-ietf-html-relrev-00.txt ftp.ics.uci.edu])
* 1996-11-13 [http://www.w3.org/Architecture/NOTE-link Describing and Linking Web Resources]
* 1997-01-23 [http://lists.gnu.org/archive/html/lynx-dev/1997-01/msg00537.html LYNX-DEV Lynx and the LINK tag]
* 1997-01-24 [http://lists.w3.org/Archives/Public/w3c-sgml-wg/1997Jan/0357.html Taxonomy list]
* 1997-03-28 [http://www.w3.org/TR/WD-htmllink-970328 W3C Working Draft: Hypertext Links and Meta Information in HTML]

=== previous attempts at documenting ===
There have been previous attempts at documenting known rel values, most of which fell out of date due to being dependent on a single author maintaining them. They're listed here purely for historical reasons, and are not sufficient to be references of their own (since they're just individual curations of other references)
* [http://fantasai.tripod.com/qref/Appendix/LinkTypes/ltdef.html Link Type Definitions Glossary] by fantasai
* ...

== related ==
{{rel-related-pages}}
* [[elemental-microformats]]
* [[existing-rev-values]]
* [[existing-class-names]]

== copyright ==

{{cc-pd-license}}

existing-rel-values

2015-03-12T12:44:07Z

Andy sky: /* Dublin Core */ Note about DCTERMS entries

<entry-title> existing rel values </entry-title>

This page contains tables of known HTML rel values from specifications, formats, proposals, brainstorms, and non-trivial [[POSH]] usage in the wild. In addition, dropped and rejected values are listed at the end for comprehensiveness.

usage: see [[rel-faq#How_is_rel_used|how is 'rel' used]]. Regarding rev, see: [[rel-faq#Should_rev_even_be_used|should 'rev' even be used]].

This page is also the official rel registry ([http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#other-link-types][http://www.w3.org/TR/html5/links.html#other-link-types]). Add new and proposed rel values to the following section:
* [[existing-rel-values#HTML5_link_type_extensions|HTML5 link type extension]]

== formats ==
These rel values are defined formats from specifications (HTML 4, microformats) are thus are recommended for general use. Alphabetically ordered by value.

Note:
* Do not add proposed rel values for HTML5 here, add them to the [[#HTML5_link_type_extensions|HTML5 link type extensions]] table.
* Do not add rel values you find in the wild to this table of rel formats, instead add them to the table in the [[existing-rel-values#POSH_usage|POSH section]].
* Do not add non-HTML rel values you find to this table of rel formats, instead add them to the table in the [[existing-rel-values#non_HTML_rel_values|non HTML rel values section]].
* Do not add rel values from obsolete/superceded proposals or drafts, instead add them to the table in the "dropped" section.

Sources:
* W3C Recommendations:
** [http://www.w3.org/TR/html401/types.html#h-6.12 HTML 4.01 section 6.12 Link types] (HTML4 Link types)
** [http://www.w3.org/TR/grddl/ Gleaning Resource Descriptions from Dialects of Languages] (GRDDL)
* [[microformats]] specifications
** [[xfn]]
** [[rel-license]]
** [[rel-nofollow]]

{| border="1"
|+
! Keyword
! Effect on <code>link</code>
! Effect on <code>a</code>, <code>area</code>
! Brief description (from the relevant specification where possible)
! Link to defining specification

|-
| [[rel-acquaintance|acquaintance]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be an acquaintance
| [[XFN]]

|-
| [[rel-alternate|alternate]]
| external resource
| external relation
| Designates substitute versions for the document in which the link occurs. When used together with the <code>lang</code> attribute, it implies a translated version of the document. When used together with the <code>media</code> attribute, it implies a version designed for a different medium (or media).
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-appendix|appendix]]
| allowed
| allowed
| Refers to a document serving as an appendix in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-bookmark|bookmark]]
| not allowed
| allowed
| Refers to a bookmark. A bookmark is a link to a key entry point within an extended document. The <code>title</code> attribute may be used, for example, to label the bookmark. Note that several bookmarks may be defined in each document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-chapter|chapter]]
| allowed
| allowed
| Refers to a document serving as a chapter in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-child|child]]
| not allowed
| external relation
| the referenced person is a child of the person represented by the current document
| [[XFN]]

|-
| [[rel-colleague|colleague]]
| not allowed
| external relation
| the referenced person is a colleague of the person represented by the current document
| [[XFN]]

|-
| [[rel-contact|contact]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be a contact
| [[XFN]]

|-
| [[rel-contents|contents]]
| allowed
| allowed
| Refers to a document serving as a table of contents. Some user agents also support the synonym ToC (from "Table of Contents").
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-copyright|copyright]]
| allowed
| allowed
| Refers to a copyright statement for the current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-co-resident|co-resident]]
| not allowed
| external relation
| the referenced person lives in the same residence as the person represented by the current document
| [[XFN]]

|-
| [[rel-co-worker|co-worker]]
| not allowed
| external relation
| the referenced person is a co-worker of the person represented by the current document
| [[XFN]]

|-
| [[rel-crush|crush]]
| not allowed
| external relation
| this person considers the referenced person to be a crush (i.e. has a crush on the referenced person)
| [[XFN]]

|-
| [[rel-date|date]]
| not allowed
| external relation
| this person considers the referenced person to be a date (i.e. is dating the referenced person)
| [[XFN]]

|-
| [[rel-friend|friend]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be a friend
| [[XFN]]

|-
| [[rel-glossary|glossary]]
| allowed
| allowed
| Refers to a document providing a list of terms and their definitions that pertain to the current document.||[http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-help|help]]
| allowed
| allowed
| Refers to a document offering help (more information, links to other sources information, etc.)
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-its-rules|its-rules]]
| allowed
| not allowed
| Refers to a document with external ITS rules.
| [http://www.w3.org/TR/its20/#selection-global-html5 Internationalization Tag Set (ITS) Version 2.0]

|-
| [[rel-kin|kin]]
| not allowed
| external relation
| the referenced person is part of the extended family of the person represented by the current document
| [[XFN]]

|-
| [[rel-license|license]]
| allowed
| allowed
| …indicates that the <nowiki>[referenced document]</nowiki> is a license for the current page.
| [[rel-license]]

|-
| [[rel-me|me]]
| external relation
| external relation
| the referenced document represents the same person as does the current document
| [[XFN]]

|-
| [[rel-met|met]]
| not allowed
| external relation
| this person has met the referenced person
| [[XFN]]

|-
| [[rel-muse|muse]]
| not allowed
| external relation
| the referenced person inspires the person represented by the current document
| [[XFN]]

|-
| [[rel-neighbor|neighbor]]
| not allowed
| external relation
| the referenced person lives nearby the person represented by the current document
| [[XFN]]

|-
| [[rel-next|next]]
| external relation
| external relation
| Refers to the next document in a linear sequence of documents. User agents may choose to preload the "next" document, to reduce the perceived load time.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-nofollow|nofollow]]
| not allowed
| external relation
| indicates that the destination of that hyperlink {{should-not}} be afforded any additional weight or ranking by user agents which perform link analysis upon web pages (e.g. search engines).
| [[rel-nofollow]]

|-
| [[rel-parent|parent]]
| not allowed
| external relation
| the referenced person is a parent of the person represented by the current document
| [[XFN]]

|-
| [[rel-prev|prev]]
| external relation
| external relation
| Refers to the previous document in an ordered series of documents. Some user agents also support the synonym "Previous".
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-previous|previous]]
| external relation
| external relation
| Synonym of <code>prev</code>
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-section|section]]
| allowed
| allowed
| Refers to a document serving as a section in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-sibling|sibling]]
| not allowed
| external relation
| the referenced person is a sibling of the person represented by the current document
| [[XFN]]

|-
| [[rel-spouse|spouse]]
| not allowed
| external relation
| the referenced person is a spouse of the person represented by the current document
| [[XFN]]

|-
| [[rel-start|start]]
| allowed
| allowed
| Refers to the first document in a collection of documents. This link type tells search engines which document is considered by the author to be the starting point of the collection.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-stylesheet|stylesheet]]
| external resource
| not allowed
| a style sheet for the current document used with the invisible <link href> element which is not ideal for content relationships. Content relationships should be user visible and thus uses with <a href> are strongly preferred. Unfortunately the use of stylesheet in user visible content like <a href> appears to be strictly theoretical.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-subsection|subsection]]
| allowed
| allowed
| Refers to a document serving as a subsection in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-sweetheart|sweetheart]]
| not allowed
| external relation
| this person considers the referenced person to be their sweetheart
| [[XFN]]

|-
| [[rel-tag|tag]]
| not allowed
| allowed
| …indicates that the <nowiki>[referenced document]</nowiki> is an author-designated "tag" (or keyword/subject) for the current page.
| [[rel-tag]]

|-
| [[rel-toc|toc]]
| allowed
| allowed
| Synonym of <code>contents</code> (from "Table Of Contents")
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-transformation|transformation]]
| allowed
| allowed
| Relates a source document to a transformation, usually represented in XSLT, that relates the source document syntax to the RDF graph syntax. Used in [[grddl|GRDDL]]
| [http://www.w3.org/TR/grddl/#transformation GRDDL]

|}

=== notes ===
*<code>rel="alternate"</code> can take further meaning from additional attributes, such as
** <code>rel="alternate" lang="fr"</code> (French language version of this page)
** <code>rel="alternate" media="print"</code> (printable version of this page)
** <code>rel="alternate" media="handheld"</code> (version of the page intended or better for handheld/portable devices like PDAs, cell phones, etc.)

*Synonyms such as "previous", "toc" are not as widely supported as the main term.

== proposals ==
A few rel values have been developed as drafts as a result of going through most of the microformats [[process]], and are thus listed here for your serious consideration. You may use these values, and if you find any problems with them please point them out on the respective "issues" page for the rel value.

{| border="1"
|+
! rel value !! summary !! proposed in !! external spec (if any)
|-
| [[rel-pronunciation|pronunciation]] || …indicates that the destination of the 'link' element is a document providing a pronunciation lexicon for speech-synthesis purposes. || [[rel-pronunciation]]
|-
| [[rel-directory|directory]] || …indicates that the destination of the hyperlink is a directory listing containing an entry for the current page. || [[rel-directory]]
|-
| [[rel-enclosure|enclosure]] || …indicates that the destination of that hyperlink is intended to be downloaded and cached. || [[rel-enclosure]] || [http://www.apps.ietf.org/rfc/rfc4287.html RFC4287]
|-
| [[rel-home|home]] || …indicates that the <nowiki>[referenced document]</nowiki> is the homepage of the site in which the current page appears. || [[rel-home]]
|-
| [[rel-payment|payment]] || …indicates that the destination of the hyperlink provides a way to show or give support (e.g. financial) for the current page|| [[rel-payment]]
|}

== HTML5 link type extensions ==

The following values are registered as link type extensions per the [http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#other-link-types requirements in the WHATWG HTML spec] and the [http://dev.w3.org/html5/spec/links.html#other-link-types requirements in the W3C HTML5 spec].

Before you register a new value:
* '''Please check the [[#formats|Formats table]] and DO NOT re-register''' rel values that are already there. Please note that the W3C HTML WG has made a [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Decision] to drop <code>index</code>, <code>up</code>, <code>first</code> and <code>last</code> from the HTML5 spec itself.
* '''Please check the [[#dropped|Dropped table]] and DO NOT register''' values that are already there. If you believe a rel value was dropped from another specification without prejudice, please provide link/cite to explicit text/decision stating as such, e.g. the value was merely postponed, or perhaps expected to be spun-out into its own spec from the group developing that specification.

Note that entries in the [[#formats|Formats table]] and entries that are already in HTML5 as built-in keywords are also considered extensions with the "Ratified" status.

Please make sure that registrations added here have all the required data filled in ''including'':
* "Effect on link"
* "Effect on a and area" and
* a link to a spec that documents the keyword ''as an HTML <code>rel</code> keyword''. (A spec that merely defines the file format of the link target but does not define the <code>rel</code> keyword for use in HTML is not the kind of spec that is being required here.)

Entries lacking any of the above required data will likely be removed.

Changes to this registry will not be reflected in validators in real time. But validators will typically get automatically updated with the changes within one week or so

{| border="1"
|+
! Keyword
! Effect on <code>link</code>
! Effect on <code>a</code>, <code>area</code>
! Brief description
! Link to specification
! Synonyms
! Status

|-
| [[rel-apple-touch-icon|apple-touch-icon]]
| External Resource
| Not allowed
| Specify a Webpage Icon for a “Web Clip”, or “touch icon”, for mobile devices (not limited to Apple devices).
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| probably redundant with rel=icon
| proposed

|-
| [[rel-apple-touch-icon-precomposed|apple-touch-icon-precomposed]]
| External Resource
| Not allowed
| Specify a Webpage Icon for a “Web Clip”, or “touch icon”, for mobile devices (not limited to Apple devices).
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| probably redundant with rel=icon
| proposed

|-
| [[rel-apple-touch-startup-image|apple-touch-startup-image]]
| External Resource
| Not allowed
| Specify a splashscreen for Web apps on iOS Safari
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| maybe redundant with rel=icon with the sizes attribute?
| proposed

|-
| [[rel-attachment|attachment]]
| Hyperlink
| Hyperlink
| The resource linked to is "attached" to this document, similar to email attachments. Used in WordPress.
| No formal specification
|
| proposed

|-
| [[WPVL_PRETTYPHOTO_REL]]
| Hyperlink
| Hyperlink
| Open lightbox with video
| No formal specification
|
| proposed

|-
| [[rel-authorization_endpoint|authorization_endpoint]]
| External Resource
| Not allowed
| Specify a hosted authorization server
| [http://indiewebcamp.com/distributed-indieauth distributed IndieAuth documentation]
|
| proposed

|-
| [[rel-canonical|canonical]]
| External Resource
| Not allowed
| Specifies the canonical URL for the current document in order to help avoid duplicate content.
| [http://en.wikipedia.org/wiki/Canonical_meta_tag Canonical meta tag] [http://www.Google.com/support/webmasters/bin/answer.py?answer=139066#2 Canonicalization at Google Webmaster Central] [http://www.Bing.com/community/site_blogs/b/webmaster/archive/2009/02/12/partnering-to-help-solve-duplicate-content-issues.aspx Microsoft Webmaster Center] [http://www.YSearchBlog.com/2009/02/12/fighting-duplication-adding-more-arrows-to-your-quiver/ Yahoo! Search Blog]
|
| proposed

|-
| [[rel-category|category]]
| Hyperlink
| Hyperlink
| Refers to a category assigned to the current document or post. Implemented by WordPress for indicating a relation between a blog post and a category.
| [[rel-category]]
|
| proposed

|-
| [[rel-component|component]]
| External Resource
| Not allowed
| Specify an HTML document that is treated as a component of this document.
| [https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/components/index.html Web Components]
|
| proposed

|-
| [[rel-chrome-webstore-item|chrome-webstore-item]]
| External Resource
| Not allowed
| Link tag to declare for app and extensions inline installations hosted in the Chrome Web Store.
| [https://developers.google.com/chrome/web-store/docs/inline_installation Using Inline Installation]
|
| proposed

|-
| [[rel-dcterms.(property)#conformsTo|DCTERMS.conformsTo]]
| External Resource
| Not allowed
| An established standard to which the described resource conforms. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.conformsTo" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#contributor|DCTERMS.contributor]]
| External Resource
| Not allowed
| An entity responsible for making contributions to the resource. Examples include a person, an organization, or a service. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.contributor" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#creator|DCTERMS.creator]]
| External Resource
| Not allowed
| An entity primarily responsible for making the resource. Examples include a person, an organization, or a service. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.creator" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#description|DCTERMS.description]]
| External Resource
| Not allowed
| An account of the resource. Description may include but is not limited to: an abstract, a table of contents, a graphical representation, or a free-text account of the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.description" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#hasFormat|DCTERMS.hasFormat]]
| External Resource
| Not allowed
| A related resource that is substantially the same as the pre-existing described resource, but in another format. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#hasPart|DCTERMS.hasPart]]
| External Resource
| Not allowed
| A related resource that is included either physically or logically in the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#hasVersion|DCTERMS.hasVersion]]
| External Resource
| Not allowed
| A related resource that is a version, edition, or adaptation of the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#identifier|DCTERMS.identifier]]
| External Resource
| Not allowed
| An unambiguous reference to the resource within a given context. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.identifier" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#isFormatOf|DCTERMS.isFormatOf]]
| External Resource
| Not allowed
| A related resource that is substantially the same as the described resource, but in another format. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isPartOf|DCTERMS.isPartOf]]
| External Resource
| Not allowed
| A related resource in which the described resource is physically or logically included. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isReferencedBy|DCTERMS.isReferencedBy]]
| External Resource
| Not allowed
| A related resource that references, cites, or otherwise points to the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isReplacedBy|DCTERMS.isReplacedBy]]
| External Resource
| Not allowed
| A related resource that supplants, displaces, or supersedes the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isRequiredBy|DCTERMS.isRequiredBy]]
| External Resource
| Not allowed
| A related resource that requires the described resource to support its function, delivery, or coherence. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isVersionOf|DCTERMS.isVersionOf]]
| External Resource
| Not allowed
| A related resource of which the described resource is a version, edition, or adaptation. Changes in version imply substantive changes in content rather than differences in format. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#license|DCTERMS.license]]
| External Resource
| Not allowed
| A legal document giving official permission to do something with the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.license" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#mediator|DCTERMS.mediator]]
| External Resource
| Not allowed
| An entity that mediates access to the resource and for whom the resource is intended or useful. In an educational context, a mediator might be a parent, teacher, teaching assistant, or care-giver. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.mediator" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#publisher|DCTERMS.publisher]]
| External Resource
| Not allowed
| An entity responsible for making the resource available. Examples include a person, an organization, or a service. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.publisher" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#references|DCTERMS.references]]
| External Resource
| Not allowed
| A related resource that is referenced, cited, or otherwise pointed to by the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#relation|DCTERMS.relation]]
| External Resource
| Not allowed
| A related resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#replaces|DCTERMS.replaces]]
| External Resource
| Not allowed
| A related resource that is supplanted, displaced, or superseded by the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#requires|DCTERMS.requires]]
| External Resource
| Not allowed
| A related resource that is required by the described resource to support its function, delivery, or coherence. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#rightsHolder|DCTERMS.rightsHolder]]
| External Resource
| Not allowed
| A person or organization owning or managing rights over the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.rightsHolder" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#source|DCTERMS.source]]
| External Resource
| Not allowed
| A related resource from which the described resource is derived. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#subject|DCTERMS.subject]]
| External Resource
| Not allowed
| The topic of the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-disclosure|disclosure]]
| Not allowed
| External Resource
| The 'disclosure' Link Relation Type designates a list of patent disclosures or a particular patent disclosure itself made with respect to material for which such relation type is specified.
| [http://tools.ietf.org/html/draft-yevstifeyev-disclosure-relation The 'disclosure' Link Relation Type]
|
| proposed

|-
| [[rel-discussion|discussion]]
| Hyperlink
| Hyperlink
| Refers to discussion of the current document or post.
| [[rel-discussion]]
|
| proposed

|-
| [[rel-dns-prefetch|dns-prefetch]]
| External Resource
| Not allowed
| Tells the browser to perform dns lookup for host names ahead of use.
| [https://developer.mozilla.org/En/Controlling_DNS_prefetching Mozilla documentation] [http://dev.chromium.org/developers/design-documents/dns-prefetching Google documentation]
|
| proposed

|-
| [[rel-edit|edit]]
| Hyperlink
| Not allowed
| Tells the browser where the current page can be edited
| [http://universaleditbutton.org/Registered_MIME_type#Alternate_Linking_Scheme Universal Edit Button Alternate Linking Scheme]. Implemented in at least [http://mediawiki.org MediaWiki].
|
| proposed

|-
| [[rel-edituri|EditURI]]
| External Resource
| Not allowed
| A blogging auto discovery value, commonly used by WordPress
| [http://bitworking.org/projects/atom/draft-gregorio-09.html#Edit AtomAPI]
|
| proposed

|-
| [[rel-enclosure|enclosure]]
| External Resource
| External Resource
| Indicates that the referred resource is intended to be downloaded and cached.
| [[rel-enclosure]]
|
| proposed

|-
| [[rel-entry-content|entry-content]]
| Not allowed
| External Resource
| Indicates that the referenced document is an alternative display source for an Internet Explorer Web Slice.
| [http://msdn.microsoft.com/en-us/library/cc304073(VS.85).aspx#_alternative Web Slice format specification 0.9]
|
| proposed

|-
| [[rel-external|external]]
| Not allowed
| Hyperlink
| Indicates that the referenced document is not part of the same site as the current document.
| [[rel-external]]
|
| proposed

|-
| [[rel-home|home]]
| Hyperlink
| Hyperlink
| Refers to the top level document for the current document. It can be combined with 'alternate' to indicate a feed for the site of the current page.
| [[rel-home]]
|
| proposed

|-
| [[rel-hub|hub]]
| Hyperlink
| Hyperlink
| Refers to a hub that enables registration for notification of updates to the current page.
| [http://pubsubhubbub.googlecode.com/svn/trunk/pubsubhubbub-core-0.3.html#discovery PubSubHubbub Spec]
|
| proposed

|-
| [[rel-in-reply-to|in-reply-to]]
| Hyperlink
| Hyperlink
| Refers to an original post that the current page is a comment on or reply to.
| [[rel-in-reply-to]]
|
| proposed

|-
| [[rel-index|index]]
| Hyperlink
| Hyperlink
| Refers to a document providing a list of topics with pointers that pertain to the current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
|
| proposed

|-
| [[rel-indieauth|indieauth]]
| External Resource
| Not allowed
| the IndieAuth server for the relying party to contact for IndieAuth authentication
| [http://spec.indieauth.com/ IndieAuth specification]
|
| proposed

|-
| [[rel-issues|issues]]
| Hyperlink
| Hyperlink
| Refers to issues regarding the current document or specification.
| [[rel-discussion]]
|
| proposed

|-
| [[rel-lightbox|lightbox]]
| Not allowed
| Img Pop-Up
| Images with this attribute are displayed in a larger way than embedded in a website (or how you specified it) when clicked (e.g. with installed "Lightbox 2"-Plugin). When adding [group] to rel="lightbox" all images get a clickable button for next/prev; insert into <code><a rel="lightbox[group]"><img src="http:example.com/img.jpg"></a></code>
| [http://lokeshdhakar.com/projects/lightbox2/ Lightbox 2] (needs actual specification to be kept in this list, this link is just documentation of one implementation)
|
| proposed

|-
| [[rel-manifest|manifest]]
| External Resource
| Not allowed
| Imports or links to a manifest
| [http://w3c.github.io/manifest/#linking W3C Manifest for web application]
|
| proposed

|-
| [[rel-meta|meta]]
| External Resource
| Not allowed
| External metadata about the HTML document
| [http://www.w3.org/TR/2004/REC-rdf-syntax-grammar-20040210/#section-rdf-in-HTML W3C's RDF/XML Syntax Specification]
|
| proposed

|-
| [[rel-indieauth|micropub]]
| External Resource
| Not allowed
| the micropub endpoint for creating new posts
| [http://indiewebcamp.com/micropub Micropub scecification]
|
| proposed

|-
| [[rel-openid.delegate|openid.delegate]]
| External Resource
| Not allowed
| When the page that contains the link is used as an OpenID indentifier, the relying party perform sOpenID 1.1 authentication with the link target as the identifier instead.
| [http://openid.net/specs/openid-authentication-1_1.html#delegating_authentication OpenID Authentication 1.1]
|
| proposed

|-
| [[rel-openid.server|openid.server]]
| External Resource
| Not allowed
| The OpenID server for the relying party to contact for OpenID 1.1 authentication
| [http://openid.net/specs/openid-authentication-1_1.html#anchor4 OpenID Authentication 1.1]
|
| proposed

|-
| [[rel-openid2.local_id|openid2.local_id]]
| External Resource
| Not allowed
| When the page that contains the link is used as an OpenID indentifier, the relying party perform sOpenID 2.0 authentication with the link target as the identifier instead.
| [http://openid.net/specs/openid-authentication-2_0.html#rfc.section.7.3.3 OpenID Authentication 2.0]
|
| proposed

|-
| [[rel-openid2.provider|openid2.provider]]
| External Resource
| Not allowed
| The OpenID server for the relying party to contact for OpenID 2.0 authentication
| [http://openid.net/specs/openid-authentication-2_0.html#rfc.section.7.3.3 OpenID Authentication 2.0]
|
| proposed

|-
| [[rel-p3pv1|p3pv1]]
| External Resource
| Not allowed
| References a machine-readable privacy policy description in the P3P format
| [http://www.w3.org/TR/P3P/#syntax_link P3P spec]
|
| proposed

|-
| [[rel-pgpkey|pgpkey]]
| External Resource
| Not allowed
| Associates a PGP key with a Web page so that the Web page URL can be used as the commenter's URL in PGP-signed blog comments and the blogging system receiving the comment can fetch the key and verify the signature as belonging to the owner of the URL.
| [http://golem.ph.utexas.edu/~distler/blog/archives/000320.html PGP-Signed Comments]
|
| proposed

|-
| [[rel-pingback|pingback]]
| External Resource
| Not allowed
| gives the address of the pingback server that handles pingbacks to the current document
| [http://www.hixie.ch/specs/pingback/pingback Pingback]
|
| proposed

|-
| [[rel-prerender|prerender]]
| External Resource
| External Resource
| Prerenders the Web page targeted by the link including running it scripts.
| [[rel-prerender]]
|
| proposed

|-
| [[rel-profile|profile]]
| External Resource
| Contextual External Resource
| indicate[s] that the destination of that hyperlink is a metadata profile (e.g. an [[XMDP]] profile) for the current page or portion thereof. See also [[xmdp-brainstorming]].
| [http://microformats.org/wiki/rel-profile rel-profile]
|
| proposed

|-
| [[rel-publisher|publisher]]
| External Resource
| External Resource
| Indicates that the referenced document is a metadata profile (e.g., a social-media/real-name profile such as a Google+ profile) for the publisher of the current page, or some portion of the current page.
| [https://support.google.com/plus/answer/1713826?hl=en Google help page]
|
| proposed

|-
| [[rel-rendition|rendition]]
| External Resource
| External Resource
| Indicates some example rendering, interpretation, or depiction of the source. User agents may choose to execute, display, or render the target in-place; or navigate to the target.
| [http://www.globalmentor.com/specs/html-rel-rendition/ HTML rel rendition]
|
| proposed

|-
| [[rel-reply-to|reply-to]]
| External Resource
| Hyperlink
| indicates any mailbox(es) (i.e. email addresses) to which responses are to be sent. ''Note: this is distinct from the 'in-reply-to' value which refers to the originating document, not to the address where comments should be sent.
| [http://tools.ietf.org/html/rfc2822 RFC2822] (originally [http://tools.ietf.org/html/rfc822#section-4.4.3 RFC822])
|
| ratified

|-
| [[rel-service|service]]
| External Resource
| Not allowed
| Atom Publishing Protocol editing service autodiscovery.
| [http://wiki.whatwg.org/wiki/ServiceRelExtension Documentation on the WHATWG wiki]
|
| proposed

|-
| [[rel-shortlink|shortlink]]
| External Resource
| Not allowed
| Specifies the preferred shortened URL for the page.
| [http://code.google.com/p/shortlink/wiki/Specification shortlink spec]
|
| proposed

|-
| [[rel-sidebar|sidebar]]
| Hyperlink
| Hyperlink
| Indicates that the referenced document is intended to be shown in a secondary browsing context.
| [[rel-sidebar]]
|
| proposed

|-
| [[rel-sitemap|sitemap]]
| External Resource
| Not allowed
| Provides a link to an XML document describing the layout of the site.
| [[rel-sitemap]]
|
| proposed

|-
| [[rel-subresource|subresource]]
| External Resource
| Not allowed
| An external resource intended for use within the current page.
| [http://www.chromium.org/spdy/link-headers-and-server-hint/link-rel-subresource Chromium documentation]
|
| proposed

|-
| [[rel-syndication|syndication]]
| Hyperlink
| Hyperlink
| Refers to a page which is a syndicated copy of the current page.
| [[rel-syndication]]
|
| proposed

|-
| [[rel-timesheet|timesheet]]
| External Resource
| Not allowed
| Applies a timesheet to the document.
| [http://www.w3.org/TR/timesheets/#smilTimesheetsNS-Elements-Timesheet non-normative section in the Timesheet spec]
|
| proposed

|-
| [[rel-token_endpoint|token_endpoint]]
| External Resource
| Not allowed
| Specify an HTTP endpoint that micropub clients can use to obtain an access token given an authorization code
| [http://indiewebcamp.com/token-endpoint token endpoint documentation]
|
| proposed

|-
| [[rel-webmention|webmention]]
| External Resource
| Hyperlink
| gives the address of the webmention endpoint that handles webmentions to the current document
| [http://webmention.org/ WebMention specification]
|
| proposed

|-
| [[rel-widget|widget]]
| External Resource
| External Resource
| Autodiscovery for W3C widgets
| [http://dev.w3.org/2006/waf/widgets/Overview.html#linking-to-a-widget-package-from-a-html- non-normative section in the Widget packaging spec]
|
| proposed

|-
| [[rel-wlwmanifest|wlwmanifest]]
| External Resource
| Not allowed
| Windows Live Writer manifest autodiscovery
| [http://msdn.microsoft.com/en-us/library/bb463263.aspx documentation on MSDN]
|
| proposed

|-
| [[rel-image_src|image_src]]
| External Resource
| Not allowed
| Specify a Webpage Icon for use by Facebook, Yahoo, Digg, etc.
| Unknown, but see for instance [http://www.niallkennedy.com/blog/2009/03/enhanced-social-share.html this]
| probably redundant with rel=icon
| proposed

|-
| [[rel-cmis-acl|http://docs.oasis-open.org/ns/cmis/link/200908/acl]]
| External Resource
| External Resource
| Identifies the resource containing a CMIS ACL document for the link context
| [http://docs.oasis-open.org/cmis/CMIS/v1.0/cs01/cmis-spec-v1.0.html#_Toc243905525 CMIS 1.0, Section 3.4.3.4]
|
| proposed

|-
| [[rel-stylesheet/less|stylesheet/less]]
| External Resource
| Not allowed
| Less CSS framework stylesheets.
| [http://lesscss.org/#-client-side-usage Less CSS usage]
|
| proposed

|}

== brainstorming ==
Several rel values are being brainstormed as potential microformats and are thus listed here. If you find you have a use for such semantics in real world examples, consider trying out these values and provide feedback on the respective brainstorming page(s) with your results and experiences.

You may list new proposed rel values here, and even better if you can list and link to POSH uses in the wild.

{| border="1"
|+
! rel value !! summary !! brainstormed in and usage in the wild

|-
| [[rel-accessibility|accessibility]] || indicate[s] that the destination of that hyperlink contains accessibility information for the current page. || [http://www.brucelawson.co.uk/2009/rel-accessibility/ blog post] which itself uses the rel value in a <link> tag in the head of the document.

|-
| [[rel-author|author]] || indicate[s] that the destination of that hyperlink represents the author of the current page. Combines with [[rel-me|rel-me]] to chain authorship information. || Google has said it will index rel-Author in this [http://googlewebmastercentral.blogspot.com/2011/06/authorship-markup-and-web-search.html blog post], with further [http://www.google.com/support/webmasters/bin/answer.py?answer=1229920 discussion of the rel-me connection] See also [http://dev.w3.org/html5/spec/Overview.html#link-type-author the HTML5 spec]

|-
| [[rel-bibliography|bibliography]] || indicate[s] that the destination of that hyperlink is a bibliography for the current page. || [http://microformats.org/discuss/mail/microformats-discuss/2007-October/010863.html mailing list post, 2007-10-15]

|-
| [[rel-cite|cite]] || indicate[s] that the destination of that hyperlink is an authoritative source or a precedent to the current page. || [[distributed-conversation-brainstorming]]

|-
| [[rel-group|group]] || the referenced document represents a group to which the person represented by the current document belongs || [[group-brainstorming]]

|-
| [[rel-jslicense|jslicense]]
| Refers to a document with JavaScript source code and license information (also called a [http://www.gnu.org/licenses/javascript-labels.html JavaScript License Web Labels] page). We might want choose a keyword for this that is more general -- there are many situations besides JavaScript in which it is desirable or required by license agreements (e.g., GNU GPL) to make an offer of both the source code and a copy of a license when distributing object code versions of a given work.
|* Brainstorming page -- thoughts on the name?
* Ex. [http://www.eff.org EFF.org] (on <code>link</code>)
* Ex. [http://www.fsf.org FSF.org] (on <code>a</code>)
|-
| [[rel-longdesc|longdesc]] || Alternative to the img longdesc attribute, for use on visible links || [http://www.google.com/search?q=rel%3D%22longdesc%22 Google search for rel=longdesc in the wild] shows many sources of proposals. Please edit this to list the earliest and perhaps most recent/comprehensive proposal. No known real world POSH usage in the wild yet.

|-
| [[rel-map|map]] || Link to a map. Possibly embedded within an adr, hCard, geo or hCalendar. Parsers {{may}} attempt to parse the URL if it is a link to a known map site (e.g. Geohash, Google Maps, Multimap) and extract co-ordinates and other useful data. || (to [[User:TobyInk|TobyInk]] by email)

|-
| [[rel-member|member]] || the referenced document represents a member of the group represented by the current document || [[group-brainstorming]]

|-
| [[rel-m_PageScroll2id|m_PageScroll2id]] || JS to scroll to a defined ID || [[group-brainstorming]]

|-
| [[rel-preconnect|preconnect]] || indicates an origin that will be used to fetch required resources. Initiating an early connection, which includes the DNS lookup, TCP handshake, and optional TLS negotiation, allows the user agent to mask the high costs of connection establishment latency.|| [https://igrigorik.github.io/resource-hints/#preconnect resource hints draft]

|-
| [[rel-prefetch|prefetch]] || indicates the URL and content-type of a resource that is likely to be a required resource when the next action or navigation is triggered. Initiating an early fetch allows the user agent to mask the request latency of the resource and make it available sooner to the application.|| [https://igrigorik.github.io/resource-hints/#prefetch resource hints draft]

|-
| [[rel-preload|preload]] || indicates the URL and content-type of a resource that should be fetched as early as possible by the user agent. Initiating an early fetch allows the user agent to mask the request latency of the resource and make it available sooner to the application.|| [https://igrigorik.github.io/resource-hints/#preload resource hints draft]

|-
| [[rel-prerender|prerender]] || indicates the URL of the next navigation target. Initiating a prerender allows the user agent to deliver an instant navigation experience: the user agent downloads the top-level resource and its assets, and performs all of the processing steps required to show the page without actually showing it to the user.|| [https://igrigorik.github.io/resource-hints/#prerender resource hints draft]

|-
| [[rel-profile|profile]] || indicate[s] that the destination of that hyperlink is a metadata profile (e.g. an [[XMDP]] profile) for the current page or portion thereof || [[xmdp-brainstorming]]

|-
| [[rel-shortlink|shortlink]] || the referenced document represents the current document but with a shorter URL || [http://samj.net/2009/04/introducing-relshort-better-alternative.html blog post]
|-
| source || the referenced document represents the source code for the current document or project || [[source-brainstorming]] [http://adactio.com/journal/6667/ blog post]

|-
| vcalendar-parent || link from an event to a containing event || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]
|-
| vcalendar-child || link from an event to a contained event || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]
|-
| vcalendar-sibling || link from an event to a related event with the same container || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]

|-
| [[rel-status|status]] || the referenced document represents the status (or source of status updates) for the author of this document || [http://monkinetic.com/2009/11/24/status-autodiscovery-relstatus.html blog post]

|}

=== more brainstorming ===
See also:
* [[genealogy-brainstorming]] for some thoughts on possible additional values for family relationships (use existing [[XFN]] [[rel-parent|parent]], [[rel-child|child]], [[rel-sibling|sibling]], [[rel-spouse|spouse]], [[rel-kin|kin]] values first though)
* [[xpn-brainstorming]] for some thoughts on possible additional values for professional relationships (use existing [[XFN]] [[rel-co-worker|co-worker]], [[rel-colleague|colleague]] values first though)

== POSH usage ==
There are numerous rel values used as [[POSH]], both in the wild, whose origins are not necessarily known, nor are their meanings consistent. There are also numerous rel values from external proposals of varying degrees of merit. It is useful to document their existence and summarize their implied meanings/usage intent as research that may be used to perhaps take one or more of them thru the microformats [[process]] if there is both sufficient interest and sufficient in the wild usage.

Note: If a value is missing from this table, it may have either already been promoted by writing it up as a proposal, or demoted by being explicitly dropped. Please check the other tables first before adding to this table.

Note: this list is incomplete, please help complete it from the following sources:

External sources:
* [http://developer.mozilla.org/about/meta Meta Information in DevMo Docs] (DevMo)
* [http://wiki.mozilla.org/Microsummaries Microsummary]
* [http://lachy.id.au/dev/markup/specs/wclr/ Web Communication Link Relationships] (WCLR)
* [http://www.w3.org/MarkUp/Relationships.html W3C Link Relationship values draft] (LRdraft) - from a draft of the HTML spec circa 1991.
* [http://www.whatwg.org/specs/web-apps/current-work/multipage/section-links.html#linkTypes HTML5 draft] '''Liable to change'''
* [http://wiki.foaf-project.org/Autodiscovery FOAF Project Wiki: Autodiscovery] (FOAF)
* [http://www.apps.ietf.org/rfc/rfc4685.html RFC4685]
* [http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html Google Blog]

{| border="1"
|+
! rel value !! summary !! origin !! proposal(s)

|-
| [[rel-archive|archive]] || index of archived entries || unknown, perhaps Wordpress open source blogging software || WCLR

|-
| [[rel-archives|archives]] || Provides a link to a collection of records, documents, or other materials of historical interest. || || HTML5

|-
|[[rel-author|author]]||see brainstorming above for suggested use by google||unknown || DevMo / HTML5

|-
| [[rel-canonical|canonical]] || To help search engines disambiguate the same page with multiple representations || Google || [http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html Google]/[http://www.bing.com/community/blogs/webmaster/archive/2009/02/12/partnering-to-help-solve-duplicate-content-issues.aspx Microsoft]/[http://www.ysearchblog.com/2009/02/12/fighting-duplication-adding-more-arrows-to-your-quiver/ Yahoo!], [http://blog.ask.com/2009/02/ask-is-going-canonical.html Ask Jeeves]

|-
| [[rel-comment|comment]] || … || … || WCLR

|-
| [[rel-contribution|contribution]] || … || … || WCLR

|-
| [[rel-edituri|EditURI]]
| Location of the xml-rpc gateway for a Wordpress install that allows external programs to add, edit and delete posts. Used by "[http://codex.wordpress.org/Weblog_Client WordPress blog client]" software for automating posting and updating blog content from your desktop. || Seen in [http://www.wordpress.org/ WordPress], e.g. [http://www.tom-watson.co.uk/]. || Description stubbed in [[rel-edituri]].

|-
| [[rel-endorsed|endorsed]] || … || … || WCLR

|-
| [[rel-fan|fan]] || xxxx. || … || [[hcard-user-profile-authoring]]

|-
| [[rel-feed|feed]] || Gives the address of a syndication feed for the current document. || … || WCLR/ HTML5

|-
| [[rel-footnote|footnote]] || Location of the footnote on a link to a footnote. || Markdown preprocessors such as [http://maruku.rubyforge.org/ Maruku] || HTML5

|-
| [[rel-icon|icon]] || Imports an icon to represent the current document. (Allowed in <code>link</code> only) || [http://dev.w3.org/html5/spec-LC/links.html#rel-icon HTML5] || WCLR/HTML5

|-
| [[rel-kinetic-stylesheet|kinetic-stylesheet]] || Imports a [http://kssproject.org/ KSS] 'kinetic stylesheet' to bind dynamic behavior to elements || Used in the [http://plone.org Plone] Content Management System || …

|-
| [[rel-lightbox|lightbox]] || Hook - Indicates that following the link will trigger a "lightbox" script (Allowed in <code>link</code> only) || ([http://www.google.co.uk/search?q=rel%3D%22lightbox%22 Google search for rel=lightbox in the wild]) || …

|-
| [[rel-lightbox|lightbox[group_name]]] || Used by lightbox scripts to group different sets of images together. Images from one group will not appear in another group's lightbox. See also "lightbox". || [http://lokeshdhakar.com/projects/lightbox2/#how Lightbox 2] || …

|-
| [[rel-prettyPhoto|prettyPhoto]] || See also "lightbox" || ([http://www.google.fr/search?q=rel%3D%22prettyphoto%22 Google search for rel="prettyphoto" in the wild]) || …

|-
| [[rel-clearbox|clearbox]] || See also "lightbox" || ([http://www.google.fr/search?q=rel%3D%22clearbox%22 Google search for rel="clearbox" in the wild]) || …

|-
| [[rel-made|made]] || … || … || LRdraft

|-
| [[rel-meta|meta]] || … || [http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/#transport 1999 W3C RDF syntax REC] || FOAF

|-
| [[rel-microsummary|microsummary]]|| … || … ||[http://wiki.mozilla.org/Microsummaries Microsummary], be aware of: [[page-summary-formats#Issues_2|microsummary issues]]

|-
| [[rel-noreferrer|noreferrer]] || indicates that no referrer information is to be leaked when following the link. || [http://dev.w3.org/html5/spec-LC/links.html#rel-noreferrer HTML5] || HTML5

|-
| [[rel-openid-delegate|openid.delegate]] || … || ([http://www.google.co.uk/search?q=%22rel%3Dopenid%22 Google search for rel=openid.* in the wild]) || …

|-
| [[rel-openid-server|openid.server]] || … || ([http://www.google.co.uk/search?q=%22rel%3Dopenid%22 Google search for rel=openid.* in the wild]) || …

|-
| [[rel-permalink|permalink]] || … || … || WCLR

|-
| [[rel-pgpkey|pgpkey]] || (see also rel-publickey) || … || [http://golem.ph.utexas.edu/~distler/blog/archives/000320.html], [http://golem.ph.utexas.edu/~distler/blog/archives/000325.html]

|-
| [[rel-pingback|pingback]] || Gives the address of the pingback server that handles pingbacks to the current document. (Allowed in <code>link</code> only) || … || WCLR/ HTML5

|-
| [[rel-popover|popover]] || Used by a JS widget to display a large, descriptive tooltip. || [http://twitter.github.com/bootstrap Twitter's Bootstrap] [http://twitter.github.com/bootstrap/javascript.html#popovers Popover.js] || …

|-
| [[rel-prefetch|prefetch]] || Specifies that the target resource should be pre-emptively cached. (Allowed in <code>link</code> only) || … || HTML5

|-
| [[rel-privacy|privacy]] || Specifies that the target resource is the privacy policy. || … || …

|-
| [[rel-publickey|publickey]] || (see also rel-pgpkey) || … || [http://rasterweb.net/raster/2002/12/12/20021212072812/]

|-
| [[rel-referral|referral]] || … || … || WCLR

|-
| [[rel-related|related]] || … || … || WCLR

|-
| [[rel-replies|replies]] || indicates a continued thread || unknown || [http://www.apps.ietf.org/rfc/rfc4685.html RFC4685]

|-
| [[rel-resource|resource]] || … || … || WCLR

|-
| [[rel-search|search]] || … || unknown || unknown

|-
| [[rel-sitemap|sitemap]] || Links to a site map document. || … || http://www.sitemaps.org/

|-
| [[rel-sponsor|sponsor]] || … || … || WCLR

|-
| [[rel-tooltip|tooltip]] || Used by a JS widget to display a tooltip similar (though more customizable) to what is shown by browsers if the 'title' attribute is present. || [http://twitter.github.com/bootstrap Twitter's Bootstrap] [http://twitter.github.com/bootstrap/javascript.html#tooltips Tooltip.js] (and likely other JS tools) || …

|-
| [[rel-trackback|trackback]] || … || unknown, perhaps open source Movable Type blogging software || WCLR

|-
| [[rel-unendorsed|unendorsed]] || (probably redundant to [[rel-nofollow|nofollow]]) || … || WCLR

|-
| [[rel-user|user]] || … || … || WCLR
|-
| [[rel-wlwmanifest|wlwmanifest]] || Used by "[http://explore.live.com/windows-live-writer Windows Live Writer]," a Microsoft [http://codex.wordpress.org/Weblog_Client blog client] for automating posting and updating blog content from your desktop. || Seen in [http://www.wordpress.org/ WordPress], e.g. [http://www.tom-watson.co.uk/]. Similar values are probably used by other blog content management systems as well. || …

|}

=== WCLR ===

The WCLR proposal is described by its author (in e-mail, 2007-09-25) as:

<blockquote>
…now effectively obsolete, since HTML5 and Microformats cover all the worthwhile relationships in that already.

These are [http://www.whatwg.org/specs/web-apps/current-work/multipage/section-links.html#linkTypes covered by HTML5 already]:

* permalink -> bookmark
* archive -> archives
* feed
* pingback
* unendorsed -> nofollow

The rest now seem unnecessary.
</blockquote>

Nonetheless, there may be some mileage in using them in microformats, at least until HTML5 is widely available.

== Dublin Core ==
In the past, Dublin Core values have been added to this page in the table about HTML5 features, but no examples, nor an actual specification explicitly stating how the value(s) should be used in HTML could be found. The linked specifications below have been updated so we should start considering Dublin Core values accordingly.

{| border="1"
|+
! rel value !! summary !! source
|-
| schema.DC || a specification of all metadata terms maintained by the Dublin Core Metadata Initiative, with regard to the fifteen terms of the Dublin Core Metadata Element Set already published || [http://www.dublincore.org/documents/dcq-html/ Dublin Core]

|-
| schema.DCTERMS || a specification of all metadata terms maintained by the Dublin Core Metadata Initiative, reflecting the changes described more fully in the 2012 document "Maintenance changes to DCMI Metadata Terms" [http://dublincore.org/usage/decisions/2012/dcterms-changes/] || [http://www.dublincore.org/documents/dcq-html/ Dublin Core]
|-
|}

'''Issues need updating given new information from linked resources.'''

Notes:
* Dublin Core. This search may help: [http://www.google.co.uk/search?as_q=rel%3Dschema.*&hl=en&num=10&btnG=Google+Search&as_epq=&as_oq=&as_eq=&lr=&as_ft=i&as_filetype=&as_qdr=all&as_occt=any&as_dt=i&as_sitesearch=http%3A%2F%2Fdublincore.org&as_rights=&safe=images].
** '''examples from that search only use invisible <code><link href></code> element'''. At first glance it appears the results from the search show only uses with the invisible <code><link href></code> element which is not ideal for content relationships. Content relationships should be user visible and thus uses with <code><a href></code> are strongly preferred.
*** [http://www.ietf.org/rfc/rfc2731.txt RFC2731] defines <code>rel="schema.AC"</code> and <code>rel="schema.RC"</code> with the pattern <code>rel="schema.PREFIX"</code> as a syntax for defining namespaces for use in meta[@name], *[@rel], *[@rev] and (as per eRDF) *[@class] attributes. A link to a Dublin Core metadata schema is generally not suitable for end users, so <code><link href></code> appears to be more appropriate than <code><a href></code> for those that use Dublin Core metadata schemas.
*** The scheme proposed above provides metadata namespace declarations. As described by DCMI specifications, such indications '''cannot''' be provided w/o a suitable namespace. In order to give complete pieces of information, the correct description set must be: <code><link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"></code> (for the namespace declaration, followed by) <code><meta name="DCTERMS.<nowiki>[element]</nowiki>" content="<nowiki>[element.value]</nowiki>"></code> for related elements.
**** Note: [http://purl.org/dc/terms/ schema.DCTERMS] is conventionally related to an upgraded elements list than [http://purl.org/dc/elements/1.1/ schema.DC] and should be preferred as rel values. Both are discussed here for subject completeness)
** '''proposal to use in content currently only theoretical'''. Thus unfortunately the use of Dublin Core in user visible content like <code><a href></code> appears to be strictly theoretical. See [http://microformats.org/discuss/mail/microformats-discuss/2008-January/011445.html microformats-discuss/2008-January/011445.html] for a proposal to use Dublin Core in user visible content.
*** '''recent improvements'''. DCMI solves some trouble concerning metadata through the ''description set model''. Some of these informations cannot currently be provided in any standard ways other than DC, namely dates, validity and periodicity. Following this public bug report ([https://www.w3.org/Bugs/Public/show_bug.cgi?format=multiple&id=22520]), the correct namespace declaration for DC and DCTERMS metadata are now considered valid HTML code. We '''must''' encourage this practice both for internal usefulness and for shared practices.

* The Dublin Core document [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] is a specification for, and gives examples of, both <link rel="schema.DC" href="http://purl.org/dc/elements/1.1/"> and <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/">. Note that Dublin Core encourages the use of DCTERMS elements over DC. A list of projects which use Dublin Core metadata is maintained [http://dublincore.org/projects/ here].
* [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] also includes examples of <link rel="DCTERMS.[element]" href="">, where [element] = subject, isReferencedBy, creator, and publisher. The <link> tag is used instead of the <meta> tag whenever the content is a URL. (Note that this use is different from, but related to, <link rel="schema.DCTERMS" href="">.) Potentially, ''any'' of the 55 DCTERMS elements could be used in this way, and this could include use in HTML 5.
** As said before, HTML5 validators now allow the use of <code><link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"></code> for namespace declarations.

* According to DCMI specification linked above, as well as [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] documentation, HTML5 @rel attribute proposed values table has been updated. It now includes a subset of DCMI ''/terms/'' namespace properties, more specifically those whose value can (or must) be logically expressed by a resource, so that the "href" attribute value becomes a non-literal value surrogate referring to the resource itself.
** Elements from ''/elements/1.1/'' namespace have not been included on purpose. According to [http://wiki.dublincore.org/index.php/FAQ/DC_and_DCTERMS_Namespaces "FAQ/DC and DCTERMS Namespaces"], the old namespace is maintained for legacy purposes only and it is not as suitable for non-literal values as the ones denoted by <code><link></code> elements.

== Use with HTTP Link Header ==
You can also use any of the rel values (that are allowed for link elements) with HTTP Link Headers,

Example: returning a Javascript file with a license (since JS itself has no way to indicate a license)
<source lang=text>
Link: <http://creativecommons.org/publicdomain/zero/1.0/>; rel="license"
</source>

For multiple licenses (e.g. CC-SA and GPL), simply use multiple <code>Link:</code> headers.
<source lang=text>
Link: <http://creativecommons.org/licenses/by-sa/3.0/>; rel="license"
Link: <http://www.gnu.org/licenses/gpl.html>; rel="license"
</source>

Example: similarly, linking to a copyright statement for an image:
<source lang=text>
Link: <http://example.org/copyright.html>; rel="copyright"
</source>
or providing a brief inline copyright statement:
<source lang=text>
Link: <data:text/plain;charset=utf-8,Copyright 2013 ExampleCo, All Rights Reserved.>; rel="copyright"
</source>

== unspecified ==
Some rel values have been added to this page perhaps in one of the tables above, but no examples, nor an actual specification explicitly stating that the value(s) should be used in the HTML 'rel' attribute could be found. They are listed here in the hopes someone can discover more specific/precise URLs to examples or specifications about them (preferably both). Until such precise URLs to examples/specs are provided, the values can be treated as they are purely theoretical and thus of little interest.

A simple list here is sufficient.

== non HTML rel values ==
There are markup languages other than HTML that also have a rel attribute, often based upon the HTML rel attribute.
It is useful to document some of these other languages and their rel values for both reference purposes, and to provide background research for the possible development and re-use of these values in HTML, as [[poshformats]] or [[microformats]]

Sources:
* [[Atom]] [[RFC4287]] specification.
* See http://www.iana.org/assignments/link-relations.html for more.
* See [http://amundsen.com/media-types/maze/format/#link-relations Maze+XML]
* See [http://amundsen.com/media-types/collection/format/#link-relations Collection+JSON]
* See [http://www.opensearch.org/Specifications/OpenSearch/1.1#Url_rel_values OpenSearch]
* See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

{| border="1"
|+
! rel value !! summary (from the relevant specification where possible)) !! defining specification

|-
| self
| From http://www.ietf.org/rfc/rfc4287.txt : <blockquote>The value "self" signifies that the IRI in the value of the href attribute identifies a resource equivalent to the containing element.</blockquote>
| [[Atom]] http://www.ietf.org/rfc/rfc4287.txt

|-
| http://gdata.youtube.com/schemas/2007#in-reply-to || See http://code.google.com/apis/youtube/2.0/developers_guide_protocol_comments.html || YouTube extension to Atom

|-
| collection || Refers to a resource which represents a collection of which the current resource is a member.

When used in the Maze+XML media type, the associated URI returns the available collection of mazes.
|| Maze+XML, Collection+JSON, OpenSearch

|-
| east || Refers to a resource to the "east" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the east in the active maze.

|| Maze+XML

|-
| exit || Refers to a resource that represents the exit or end of the current client actvity or process.

When used in the Maze+XML media type, the associated URI points to the final exit resource of the active maze.

|| Maze+XML

|-
| north || Refers to a resource that is "north" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the north in the active maze.

|| Maze+XML

|-
| south || Refers to a resource that is "south" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the south in the active maze.

|| Maze+XML

|-
| [[rel-via|via]] || Identifies a resource that is the source of the information in the context. || Atom 1.0 Syndication format (RFC 4287)

|-
| west || Refers to a resource that is "west" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the west in the active maze.

|| Maze+XML

|-
| item || The target IRI points to a resource that is a member of a collection represented by the context IRI. || Collection+JSON

|-
| create-form || When included in a resource, the "create-form" link relation MAY identify a target resource that represents the form to append a new member to the link context. || See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

|-
| edit-form || When included in a resource, the "edit-form" link relation identifies a target resource that represents the form for editing associated resource. || See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

|-
| lightframe || Opens the target in a lightbox. On inclusion it provides a simple target the lightframe and loads the content in a lightbox effect || Lightbox

|-
| superbox[image] || jQuery Superbox! is a script which allows you display windows with the lightbox effect. || superbox

|-
| wp-video-lightbox || wp-video-lightbox! is a rel to anchor tag script display videos with the lightbox effect. || wp-video-lightbox

|-
| youtube || Opens the target youtube video in using the Swipebox Plugin || Swipebox

|-
| shadowbox || shadowbox is a jQuery script for images displaying with the "lightbox" effects. || shadowbox

|-
| permission || When included in a resource, the "permission" link relation MAY identify a target resource that represents the list of entities that can access or modify the resource in the link context. || See [http://cdoc.io/spec.html#permission-link-relation Collection Document Media Type Specification]

|-
| version-history
| When included on a versioned resource, this link points to a resource containing the version history for this resource.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| latest-version
| When included on a versioned resource, this link points to a resource containing the latest (e.g., current) version.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| working-copy
| When included on a versioned resource, this link points to a working copy for this resource.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| working-copy-of
| When included on a working copy, this link points to the versioned resource from which this working copy was obtained.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| predecessor-version
| When included on a versioned resource, this link points to a resource containing the predecessor version in the version history.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| successor-version
| When included on a versioned resource, this link points to a resource containing the successor version in the version history.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| ... || ... || ...

|}

== dropped ==
The following rel values were in earlier version(s) of specification(s) and it is presumed by their absence from the most recent version of the respective specification(s) that they have been deprecated or obsoleted.

In general, you {{should not}} use any dropped values.

If any such values have been superceded by standard values (see the first table on this page), then you {{must not}} use the dropped versions.

In particular:
* if a rel value was in a draft and is missing (without explanation) from the final spec, or
* if a rel value was in a previous version of and is missing (without explanation) from an update to the specification (even a draft update)

Then absent any other information or explanation, it is presumed that the group/editors working on that specification decided to explicitly drop it (either in development, or in the updated version) and thus it should be obsoleted (not re-registered).

If you wish to add them, please research why such values were omitted from latter specifications before doing so. If you do discover the reasoning, please add a short statement or link to thereof into the appropriate place in the following table.

If there is more data, e.g. a link to an email of discussion of the spec development that explains ''why'' the rel value was dropped, and it explicitly states, e.g. it was without prejudice, or merely post-poned, or perhaps expected to be spun-out into its spec (or some other explicit positive reason), then it makes to link/cite that explicit text as part of a proposal.

Sources:
* [http://www.w3.org/MarkUp/html3/ HTML3] (HTML3) / has been superceded by [http://www.w3.org/MarkUp/Wilbur/ HTML 3.2] - which itself has been superceded by [http://www.w3.org/TR/REC-html40 HTML 4.0] - which itself has been updated by [http://w3.org/TR/html401 HTML 4.01], commonly referred to as "HTML 4" in this wiki and other places.)
* [http://www.w3.org/TR/relations.html Proposed HTML 4.0 link types] (HTML4dropped) - obsoleted/superceded by the HTML 4.0 Recommendation. Any values that were in the "Proposed HTML 4.0 link types" document but didn't make it into the HTML 4.0 Recommendation were thus explicitly dropped and should be avoided.

{| border="1"
|+
! rel value !! summary !! defining specification !! why dropped

|-
|[[rel-banner|banner]]||Was used to reference another document to be used as banner for this document (i.e. a form of "include" statement).|| HTML3 ||unknown

|-
| [[rel-begin|begin]] || identifies the author-defined start of a sequence of documents of which the current document is a node.
|| HTML4dropped||unknown

|-
| [[rel-biblioentry|biblioentry]] || identifies a bibliographic entry || HTML4dropped||unknown

|-
| [[rel-bibliography|bibliography]] || identifies a bibliography || HTML4dropped||unknown

|-
| [[rel-child|child]] (obsolete/superceded) || the target document is a hierarchical child, or subdocument, of the current document|| HTML4dropped||unknown

|-
| [[rel-citation|citation]] || the target is a bibliographic citation || HTML4dropped||unknown

|-
| [[rel-collection|collection]] || the target document is an collection that contains the current document || HTML4dropped||unknown

|-
| [[rel-definition|definition]] || identifies a definition of a term || HTML4dropped||unknown

|-
| [[rel-disclaimer|disclaimer]] || identifies a hypertext link to a legal disclaimer || HTML4dropped||unknown

|-
| [[rel-editor|editor]] || identifies a hypertext link to an editor || HTML4dropped||unknown

|-
| [[rel-end|end]] || identifies the author-defined end of a sequence of documents of which the current document is a node. || HTML4dropped||unknown

|-
| [[rel-footnote|footnote]] || the anchor is a footnote marker and the target is a footnote || HTML4dropped||unknown

|-
| [[rel-navigate|navigate]] || the target document contains information such as a image map that will help users to gain a sense of how and where to found information || HTML4dropped||unknown

|-
| [[rel-origin|origin]] || synonym for <code>top</code> || HTML4dropped||unknown

|-
| [[rel-parent|parent]] (obsolete/superceded) || the target document is the hierarchical parent, or container, of the current document|| HTML4dropped||unknown

|-
| [[rel-pointer|pointer]] || the target is a pointer to the real target. This value can be used by a user agent to perform a pre-fetch of the specified target for evaluation until the real target is reached || HTML4dropped||unknown

|-
| [[rel-publisher|publisher]] || identifies a hypertext link to a publisher || HTML4dropped||unknown

|-
| [[rel-sibling|sibling]] (obsolete/superceded) || the target document is a child of a common parent, or a hierarchical peer of the current document|| HTML4dropped||unknown

|-
| [[rel-top|top]] || the target document is the logical top node of the tree (see also <code>begin</code>) || HTML4dropped||unknown

|-
| [[rel-trademark|trademark]] || identifies a hypertext link to a trademark notice || HTML4dropped||unknown

|-
| [[rel-translation|translation]] || the target is a translation to another language || HTML4dropped||unknown

|-
| [[rel-urc|urc]] || identifies a Universal Resource Citation || HTML4dropped||unknown

|-
|}

== dropped without prejudice ==
In one known instance (from HTML4 to HTML5), some rel values were in an earlier version of a specification (or a proposal) and were dropped from a latter (draft) version, and it was noted that these values were dropped with the intent that they could still be proposed in a registry and thus they explicitly were not deprecated or obsoleted. This section documents such values as separate from the [[#dropped|dropped]] section.

In general, you {{should not}} use any dropped values.

If any such values have been superceded by standard values (see the first table on this page), then you {{must not}} use the dropped versions.

Rel values that were dropped without prejudice from a specification will be considered similar to new values that have never been specified.

If you know of additional rel values that were dropped without prejudice from an update to a specification, please cite a URL and quote from the group developing the specification that officially states from that group that the dropping of the values was done without prejudice, or equivalent statement (such as explicit allowance of external registration, proposal, and/or development).

This table serves a historical purpose. If you wish to propose a value from this table, please copy it and leave it in place.

Sources:
* Several rel values were [http://www.w3.org/Bugs/Public/show_bug.cgi?id=7475#c15 explicitly dropped from HTML5]. Per: [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Issue 118 Decision] ('''emphasis''' added): <blockquote>"The final proposal argues for the removal of some relation values, to wit, it suggests removal of '''index, up, first and last'''. It was pointed out in survey comments that these relations are already registered in the IANA link relation registry. Presumably, '''these relations could also be entered in whatever other registry or registries HTML5 adopts for this purpose'''...."Next Steps..."Since the relations to be removed are already registered at the IANA link relation registry, no further action is needed to include them there. WG members are '''free to register or record these relations elsehwere''' [sic], as well."</blockquote>

{| border="1"
|+
! rel value
! summary
! defining specification
! why dropped

|-
| [[rel-first|first]]
| synonym for <code>begin</code>
| HTML4dropped - never in an official spec
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-index|index]]
| Refers to a document providing an index for the current document.
| was in [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-last|last]]
| synonym for <code>end</code>
| HTML4dropped - never in an official spec
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-up|up]]
|When the document forms part of a hierarchy, this link references the immediate parent of the current document.
| was in [http://www.w3.org/MarkUp/html3/dochead.html HTML3] - but [http://www.w3.org/TR/html401/types.html#type-links dropped in HTML4]
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
|}

See related [http://dev.w3.org/html5/spec/links.html#linkTypes HTML5: Link types] for existing HTML5 specified rel values.

== rejected ==
Some rel values have been proposed and rejected. They are listed here to make that explicit. Authors {{must not}} use rejected rel values.

Source: [[rejected-formats]].

{| border="1"
|+
! rel value !! origin / proposal !! why rejected
|-
| [[rel-logo|logo]]
| [http://relogo.org Relogo.org]
| [[rejected-formats#Logo]]
|-
|[[rel-pavatar|pavatar]] || [http://pavatar.com/ pavatar] || [[rejected-formats#Pavatar]]
|-
|}

== tools ==
See [[implementations]].

== addtional external research ==
Here are some additional historical references to the development or rel-values which may be useful when researching values, especially why specific values may have been proposed but abandoned.
* 1996-06-07 [http://www.w3.org/MarkUp/draft-ietf-html-relrev-00.txt Hypertext links in HTML] (copies: [http://ftp.ics.uci.edu/pub/ietf/html/draft-ietf-html-relrev-00.txt ftp.ics.uci.edu])
* 1996-11-13 [http://www.w3.org/Architecture/NOTE-link Describing and Linking Web Resources]
* 1997-01-23 [http://lists.gnu.org/archive/html/lynx-dev/1997-01/msg00537.html LYNX-DEV Lynx and the LINK tag]
* 1997-01-24 [http://lists.w3.org/Archives/Public/w3c-sgml-wg/1997Jan/0357.html Taxonomy list]
* 1997-03-28 [http://www.w3.org/TR/WD-htmllink-970328 W3C Working Draft: Hypertext Links and Meta Information in HTML]

=== previous attempts at documenting ===
There have been previous attempts at documenting known rel values, most of which fell out of date due to being dependent on a single author maintaining them. They're listed here purely for historical reasons, and are not sufficient to be references of their own (since they're just individual curations of other references)
* [http://fantasai.tripod.com/qref/Appendix/LinkTypes/ltdef.html Link Type Definitions Glossary] by fantasai
* ...

== related ==
{{rel-related-pages}}
* [[elemental-microformats]]
* [[existing-rev-values]]
* [[existing-class-names]]

== copyright ==

{{cc-pd-license}}

existing-rel-values

2015-03-11T15:58:23Z

Andy sky: /* HTML5 link type extensions */ Dublin Core nonliteral-type resource references

<entry-title> existing rel values </entry-title>

This page contains tables of known HTML rel values from specifications, formats, proposals, brainstorms, and non-trivial [[POSH]] usage in the wild. In addition, dropped and rejected values are listed at the end for comprehensiveness.

usage: see [[rel-faq#How_is_rel_used|how is 'rel' used]]. Regarding rev, see: [[rel-faq#Should_rev_even_be_used|should 'rev' even be used]].

This page is also the official rel registry ([http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#other-link-types][http://www.w3.org/TR/html5/links.html#other-link-types]). Add new and proposed rel values to the following section:
* [[existing-rel-values#HTML5_link_type_extensions|HTML5 link type extension]]

== formats ==
These rel values are defined formats from specifications (HTML 4, microformats) are thus are recommended for general use. Alphabetically ordered by value.

Note:
* Do not add proposed rel values for HTML5 here, add them to the [[#HTML5_link_type_extensions|HTML5 link type extensions]] table.
* Do not add rel values you find in the wild to this table of rel formats, instead add them to the table in the [[existing-rel-values#POSH_usage|POSH section]].
* Do not add non-HTML rel values you find to this table of rel formats, instead add them to the table in the [[existing-rel-values#non_HTML_rel_values|non HTML rel values section]].
* Do not add rel values from obsolete/superceded proposals or drafts, instead add them to the table in the "dropped" section.

Sources:
* W3C Recommendations:
** [http://www.w3.org/TR/html401/types.html#h-6.12 HTML 4.01 section 6.12 Link types] (HTML4 Link types)
** [http://www.w3.org/TR/grddl/ Gleaning Resource Descriptions from Dialects of Languages] (GRDDL)
* [[microformats]] specifications
** [[xfn]]
** [[rel-license]]
** [[rel-nofollow]]

{| border="1"
|+
! Keyword
! Effect on <code>link</code>
! Effect on <code>a</code>, <code>area</code>
! Brief description (from the relevant specification where possible)
! Link to defining specification

|-
| [[rel-acquaintance|acquaintance]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be an acquaintance
| [[XFN]]

|-
| [[rel-alternate|alternate]]
| external resource
| external relation
| Designates substitute versions for the document in which the link occurs. When used together with the <code>lang</code> attribute, it implies a translated version of the document. When used together with the <code>media</code> attribute, it implies a version designed for a different medium (or media).
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-appendix|appendix]]
| allowed
| allowed
| Refers to a document serving as an appendix in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-bookmark|bookmark]]
| not allowed
| allowed
| Refers to a bookmark. A bookmark is a link to a key entry point within an extended document. The <code>title</code> attribute may be used, for example, to label the bookmark. Note that several bookmarks may be defined in each document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-chapter|chapter]]
| allowed
| allowed
| Refers to a document serving as a chapter in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-child|child]]
| not allowed
| external relation
| the referenced person is a child of the person represented by the current document
| [[XFN]]

|-
| [[rel-colleague|colleague]]
| not allowed
| external relation
| the referenced person is a colleague of the person represented by the current document
| [[XFN]]

|-
| [[rel-contact|contact]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be a contact
| [[XFN]]

|-
| [[rel-contents|contents]]
| allowed
| allowed
| Refers to a document serving as a table of contents. Some user agents also support the synonym ToC (from "Table of Contents").
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-copyright|copyright]]
| allowed
| allowed
| Refers to a copyright statement for the current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-co-resident|co-resident]]
| not allowed
| external relation
| the referenced person lives in the same residence as the person represented by the current document
| [[XFN]]

|-
| [[rel-co-worker|co-worker]]
| not allowed
| external relation
| the referenced person is a co-worker of the person represented by the current document
| [[XFN]]

|-
| [[rel-crush|crush]]
| not allowed
| external relation
| this person considers the referenced person to be a crush (i.e. has a crush on the referenced person)
| [[XFN]]

|-
| [[rel-date|date]]
| not allowed
| external relation
| this person considers the referenced person to be a date (i.e. is dating the referenced person)
| [[XFN]]

|-
| [[rel-friend|friend]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be a friend
| [[XFN]]

|-
| [[rel-glossary|glossary]]
| allowed
| allowed
| Refers to a document providing a list of terms and their definitions that pertain to the current document.||[http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-help|help]]
| allowed
| allowed
| Refers to a document offering help (more information, links to other sources information, etc.)
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-its-rules|its-rules]]
| allowed
| not allowed
| Refers to a document with external ITS rules.
| [http://www.w3.org/TR/its20/#selection-global-html5 Internationalization Tag Set (ITS) Version 2.0]

|-
| [[rel-kin|kin]]
| not allowed
| external relation
| the referenced person is part of the extended family of the person represented by the current document
| [[XFN]]

|-
| [[rel-license|license]]
| allowed
| allowed
| …indicates that the <nowiki>[referenced document]</nowiki> is a license for the current page.
| [[rel-license]]

|-
| [[rel-me|me]]
| external relation
| external relation
| the referenced document represents the same person as does the current document
| [[XFN]]

|-
| [[rel-met|met]]
| not allowed
| external relation
| this person has met the referenced person
| [[XFN]]

|-
| [[rel-muse|muse]]
| not allowed
| external relation
| the referenced person inspires the person represented by the current document
| [[XFN]]

|-
| [[rel-neighbor|neighbor]]
| not allowed
| external relation
| the referenced person lives nearby the person represented by the current document
| [[XFN]]

|-
| [[rel-next|next]]
| external relation
| external relation
| Refers to the next document in a linear sequence of documents. User agents may choose to preload the "next" document, to reduce the perceived load time.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-nofollow|nofollow]]
| not allowed
| external relation
| indicates that the destination of that hyperlink {{should-not}} be afforded any additional weight or ranking by user agents which perform link analysis upon web pages (e.g. search engines).
| [[rel-nofollow]]

|-
| [[rel-parent|parent]]
| not allowed
| external relation
| the referenced person is a parent of the person represented by the current document
| [[XFN]]

|-
| [[rel-prev|prev]]
| external relation
| external relation
| Refers to the previous document in an ordered series of documents. Some user agents also support the synonym "Previous".
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-previous|previous]]
| external relation
| external relation
| Synonym of <code>prev</code>
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-section|section]]
| allowed
| allowed
| Refers to a document serving as a section in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-sibling|sibling]]
| not allowed
| external relation
| the referenced person is a sibling of the person represented by the current document
| [[XFN]]

|-
| [[rel-spouse|spouse]]
| not allowed
| external relation
| the referenced person is a spouse of the person represented by the current document
| [[XFN]]

|-
| [[rel-start|start]]
| allowed
| allowed
| Refers to the first document in a collection of documents. This link type tells search engines which document is considered by the author to be the starting point of the collection.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-stylesheet|stylesheet]]
| external resource
| not allowed
| a style sheet for the current document used with the invisible <link href> element which is not ideal for content relationships. Content relationships should be user visible and thus uses with <a href> are strongly preferred. Unfortunately the use of stylesheet in user visible content like <a href> appears to be strictly theoretical.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-subsection|subsection]]
| allowed
| allowed
| Refers to a document serving as a subsection in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-sweetheart|sweetheart]]
| not allowed
| external relation
| this person considers the referenced person to be their sweetheart
| [[XFN]]

|-
| [[rel-tag|tag]]
| not allowed
| allowed
| …indicates that the <nowiki>[referenced document]</nowiki> is an author-designated "tag" (or keyword/subject) for the current page.
| [[rel-tag]]

|-
| [[rel-toc|toc]]
| allowed
| allowed
| Synonym of <code>contents</code> (from "Table Of Contents")
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-transformation|transformation]]
| allowed
| allowed
| Relates a source document to a transformation, usually represented in XSLT, that relates the source document syntax to the RDF graph syntax. Used in [[grddl|GRDDL]]
| [http://www.w3.org/TR/grddl/#transformation GRDDL]

|}

=== notes ===
*<code>rel="alternate"</code> can take further meaning from additional attributes, such as
** <code>rel="alternate" lang="fr"</code> (French language version of this page)
** <code>rel="alternate" media="print"</code> (printable version of this page)
** <code>rel="alternate" media="handheld"</code> (version of the page intended or better for handheld/portable devices like PDAs, cell phones, etc.)

*Synonyms such as "previous", "toc" are not as widely supported as the main term.

== proposals ==
A few rel values have been developed as drafts as a result of going through most of the microformats [[process]], and are thus listed here for your serious consideration. You may use these values, and if you find any problems with them please point them out on the respective "issues" page for the rel value.

{| border="1"
|+
! rel value !! summary !! proposed in !! external spec (if any)
|-
| [[rel-pronunciation|pronunciation]] || …indicates that the destination of the 'link' element is a document providing a pronunciation lexicon for speech-synthesis purposes. || [[rel-pronunciation]]
|-
| [[rel-directory|directory]] || …indicates that the destination of the hyperlink is a directory listing containing an entry for the current page. || [[rel-directory]]
|-
| [[rel-enclosure|enclosure]] || …indicates that the destination of that hyperlink is intended to be downloaded and cached. || [[rel-enclosure]] || [http://www.apps.ietf.org/rfc/rfc4287.html RFC4287]
|-
| [[rel-home|home]] || …indicates that the <nowiki>[referenced document]</nowiki> is the homepage of the site in which the current page appears. || [[rel-home]]
|-
| [[rel-payment|payment]] || …indicates that the destination of the hyperlink provides a way to show or give support (e.g. financial) for the current page|| [[rel-payment]]
|}

== HTML5 link type extensions ==

The following values are registered as link type extensions per the [http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#other-link-types requirements in the WHATWG HTML spec] and the [http://dev.w3.org/html5/spec/links.html#other-link-types requirements in the W3C HTML5 spec].

Before you register a new value:
* '''Please check the [[#formats|Formats table]] and DO NOT re-register''' rel values that are already there. Please note that the W3C HTML WG has made a [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Decision] to drop <code>index</code>, <code>up</code>, <code>first</code> and <code>last</code> from the HTML5 spec itself.
* '''Please check the [[#dropped|Dropped table]] and DO NOT register''' values that are already there. If you believe a rel value was dropped from another specification without prejudice, please provide link/cite to explicit text/decision stating as such, e.g. the value was merely postponed, or perhaps expected to be spun-out into its own spec from the group developing that specification.

Note that entries in the [[#formats|Formats table]] and entries that are already in HTML5 as built-in keywords are also considered extensions with the "Ratified" status.

Please make sure that registrations added here have all the required data filled in ''including'':
* "Effect on link"
* "Effect on a and area" and
* a link to a spec that documents the keyword ''as an HTML <code>rel</code> keyword''. (A spec that merely defines the file format of the link target but does not define the <code>rel</code> keyword for use in HTML is not the kind of spec that is being required here.)

Entries lacking any of the above required data will likely be removed.

Changes to this registry will not be reflected in validators in real time. But validators will typically get automatically updated with the changes within one week or so

{| border="1"
|+
! Keyword
! Effect on <code>link</code>
! Effect on <code>a</code>, <code>area</code>
! Brief description
! Link to specification
! Synonyms
! Status

|-
| [[rel-apple-touch-icon|apple-touch-icon]]
| External Resource
| Not allowed
| Specify a Webpage Icon for a “Web Clip”, or “touch icon”, for mobile devices (not limited to Apple devices).
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| probably redundant with rel=icon
| proposed

|-
| [[rel-apple-touch-icon-precomposed|apple-touch-icon-precomposed]]
| External Resource
| Not allowed
| Specify a Webpage Icon for a “Web Clip”, or “touch icon”, for mobile devices (not limited to Apple devices).
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| probably redundant with rel=icon
| proposed

|-
| [[rel-apple-touch-startup-image|apple-touch-startup-image]]
| External Resource
| Not allowed
| Specify a splashscreen for Web apps on iOS Safari
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| maybe redundant with rel=icon with the sizes attribute?
| proposed

|-
| [[rel-attachment|attachment]]
| Hyperlink
| Hyperlink
| The resource linked to is "attached" to this document, similar to email attachments. Used in WordPress.
| No formal specification
|
| proposed

|-
| [[WPVL_PRETTYPHOTO_REL]]
| Hyperlink
| Hyperlink
| Open lightbox with video
| No formal specification
|
| proposed

|-
| [[rel-authorization_endpoint|authorization_endpoint]]
| External Resource
| Not allowed
| Specify a hosted authorization server
| [http://indiewebcamp.com/distributed-indieauth distributed IndieAuth documentation]
|
| proposed

|-
| [[rel-canonical|canonical]]
| External Resource
| Not allowed
| Specifies the canonical URL for the current document in order to help avoid duplicate content.
| [http://en.wikipedia.org/wiki/Canonical_meta_tag Canonical meta tag] [http://www.Google.com/support/webmasters/bin/answer.py?answer=139066#2 Canonicalization at Google Webmaster Central] [http://www.Bing.com/community/site_blogs/b/webmaster/archive/2009/02/12/partnering-to-help-solve-duplicate-content-issues.aspx Microsoft Webmaster Center] [http://www.YSearchBlog.com/2009/02/12/fighting-duplication-adding-more-arrows-to-your-quiver/ Yahoo! Search Blog]
|
| proposed

|-
| [[rel-category|category]]
| Hyperlink
| Hyperlink
| Refers to a category assigned to the current document or post. Implemented by WordPress for indicating a relation between a blog post and a category.
| [[rel-category]]
|
| proposed

|-
| [[rel-component|component]]
| External Resource
| Not allowed
| Specify an HTML document that is treated as a component of this document.
| [https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/components/index.html Web Components]
|
| proposed

|-
| [[rel-chrome-webstore-item|chrome-webstore-item]]
| External Resource
| Not allowed
| Link tag to declare for app and extensions inline installations hosted in the Chrome Web Store.
| [https://developers.google.com/chrome/web-store/docs/inline_installation Using Inline Installation]
|
| proposed

|-
| [[rel-dcterms.(property)#conformsTo|DCTERMS.conformsTo]]
| External Resource
| Not allowed
| An established standard to which the described resource conforms. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.conformsTo" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#contributor|DCTERMS.contributor]]
| External Resource
| Not allowed
| An entity responsible for making contributions to the resource. Examples include a person, an organization, or a service. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.contributor" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#creator|DCTERMS.creator]]
| External Resource
| Not allowed
| An entity primarily responsible for making the resource. Examples include a person, an organization, or a service. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.creator" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#description|DCTERMS.description]]
| External Resource
| Not allowed
| An account of the resource. Description may include but is not limited to: an abstract, a table of contents, a graphical representation, or a free-text account of the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.description" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#hasFormat|DCTERMS.hasFormat]]
| External Resource
| Not allowed
| A related resource that is substantially the same as the pre-existing described resource, but in another format. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#hasPart|DCTERMS.hasPart]]
| External Resource
| Not allowed
| A related resource that is included either physically or logically in the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#hasVersion|DCTERMS.hasVersion]]
| External Resource
| Not allowed
| A related resource that is a version, edition, or adaptation of the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#identifier|DCTERMS.identifier]]
| External Resource
| Not allowed
| An unambiguous reference to the resource within a given context. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.identifier" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#isFormatOf|DCTERMS.isFormatOf]]
| External Resource
| Not allowed
| A related resource that is substantially the same as the described resource, but in another format. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isPartOf|DCTERMS.isPartOf]]
| External Resource
| Not allowed
| A related resource in which the described resource is physically or logically included. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isReferencedBy|DCTERMS.isReferencedBy]]
| External Resource
| Not allowed
| A related resource that references, cites, or otherwise points to the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isReplacedBy|DCTERMS.isReplacedBy]]
| External Resource
| Not allowed
| A related resource that supplants, displaces, or supersedes the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isRequiredBy|DCTERMS.isRequiredBy]]
| External Resource
| Not allowed
| A related resource that requires the described resource to support its function, delivery, or coherence. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#isVersionOf|DCTERMS.isVersionOf]]
| External Resource
| Not allowed
| A related resource of which the described resource is a version, edition, or adaptation. Changes in version imply substantive changes in content rather than differences in format. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#license|DCTERMS.license]]
| External Resource
| Not allowed
| A legal document giving official permission to do something with the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.license" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#mediator|DCTERMS.mediator]]
| External Resource
| Not allowed
| An entity that mediates access to the resource and for whom the resource is intended or useful. In an educational context, a mediator might be a parent, teacher, teaching assistant, or care-giver. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.mediator" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#publisher|DCTERMS.publisher]]
| External Resource
| Not allowed
| An entity responsible for making the resource available. Examples include a person, an organization, or a service. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.publisher" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#references|DCTERMS.references]]
| External Resource
| Not allowed
| A related resource that is referenced, cited, or otherwise pointed to by the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#relation|DCTERMS.relation]]
| External Resource
| Not allowed
| A related resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#replaces|DCTERMS.replaces]]
| External Resource
| Not allowed
| A related resource that is supplanted, displaced, or superseded by the described resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#requires|DCTERMS.requires]]
| External Resource
| Not allowed
| A related resource that is required by the described resource to support its function, delivery, or coherence. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#rightsHolder|DCTERMS.rightsHolder]]
| External Resource
| Not allowed
| A person or organization owning or managing rights over the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.rightsHolder" content="..." /></code>
| proposed

|-
| [[rel-dcterms.(property)#source|DCTERMS.source]]
| External Resource
| Not allowed
| A related resource from which the described resource is derived. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-dcterms.(property)#subject|DCTERMS.subject]]
| External Resource
| Not allowed
| The topic of the resource. 
Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-disclosure|disclosure]]
| Not allowed
| External Resource
| The 'disclosure' Link Relation Type designates a list of patent disclosures or a particular patent disclosure itself made with respect to material for which such relation type is specified.
| [http://tools.ietf.org/html/draft-yevstifeyev-disclosure-relation The 'disclosure' Link Relation Type]
|
| proposed

|-
| [[rel-discussion|discussion]]
| Hyperlink
| Hyperlink
| Refers to discussion of the current document or post.
| [[rel-discussion]]
|
| proposed

|-
| [[rel-dns-prefetch|dns-prefetch]]
| External Resource
| Not allowed
| Tells the browser to perform dns lookup for host names ahead of use.
| [https://developer.mozilla.org/En/Controlling_DNS_prefetching Mozilla documentation] [http://dev.chromium.org/developers/design-documents/dns-prefetching Google documentation]
|
| proposed

|-
| [[rel-edit|edit]]
| Hyperlink
| Not allowed
| Tells the browser where the current page can be edited
| [http://universaleditbutton.org/Registered_MIME_type#Alternate_Linking_Scheme Universal Edit Button Alternate Linking Scheme]. Implemented in at least [http://mediawiki.org MediaWiki].
|
| proposed

|-
| [[rel-edituri|EditURI]]
| External Resource
| Not allowed
| A blogging auto discovery value, commonly used by WordPress
| [http://bitworking.org/projects/atom/draft-gregorio-09.html#Edit AtomAPI]
|
| proposed

|-
| [[rel-enclosure|enclosure]]
| External Resource
| External Resource
| Indicates that the referred resource is intended to be downloaded and cached.
| [[rel-enclosure]]
|
| proposed

|-
| [[rel-entry-content|entry-content]]
| Not allowed
| External Resource
| Indicates that the referenced document is an alternative display source for an Internet Explorer Web Slice.
| [http://msdn.microsoft.com/en-us/library/cc304073(VS.85).aspx#_alternative Web Slice format specification 0.9]
|
| proposed

|-
| [[rel-external|external]]
| Not allowed
| Hyperlink
| Indicates that the referenced document is not part of the same site as the current document.
| [[rel-external]]
|
| proposed

|-
| [[rel-home|home]]
| Hyperlink
| Hyperlink
| Refers to the top level document for the current document. It can be combined with 'alternate' to indicate a feed for the site of the current page.
| [[rel-home]]
|
| proposed

|-
| [[rel-hub|hub]]
| Hyperlink
| Hyperlink
| Refers to a hub that enables registration for notification of updates to the current page.
| [http://pubsubhubbub.googlecode.com/svn/trunk/pubsubhubbub-core-0.3.html#discovery PubSubHubbub Spec]
|
| proposed

|-
| [[rel-in-reply-to|in-reply-to]]
| Hyperlink
| Hyperlink
| Refers to an original post that the current page is a comment on or reply to.
| [[rel-in-reply-to]]
|
| proposed

|-
| [[rel-index|index]]
| Hyperlink
| Hyperlink
| Refers to a document providing a list of topics with pointers that pertain to the current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
|
| proposed

|-
| [[rel-indieauth|indieauth]]
| External Resource
| Not allowed
| the IndieAuth server for the relying party to contact for IndieAuth authentication
| [http://spec.indieauth.com/ IndieAuth specification]
|
| proposed

|-
| [[rel-issues|issues]]
| Hyperlink
| Hyperlink
| Refers to issues regarding the current document or specification.
| [[rel-discussion]]
|
| proposed

|-
| [[rel-lightbox|lightbox]]
| Not allowed
| Img Pop-Up
| Images with this attribute are displayed in a larger way than embedded in a website (or how you specified it) when clicked (e.g. with installed "Lightbox 2"-Plugin). When adding [group] to rel="lightbox" all images get a clickable button for next/prev; insert into <code><a rel="lightbox[group]"><img src="http:example.com/img.jpg"></a></code>
| [http://lokeshdhakar.com/projects/lightbox2/ Lightbox 2] (needs actual specification to be kept in this list, this link is just documentation of one implementation)
|
| proposed

|-
| [[rel-manifest|manifest]]
| External Resource
| Not allowed
| Imports or links to a manifest
| [http://w3c.github.io/manifest/#linking W3C Manifest for web application]
|
| proposed

|-
| [[rel-meta|meta]]
| External Resource
| Not allowed
| External metadata about the HTML document
| [http://www.w3.org/TR/2004/REC-rdf-syntax-grammar-20040210/#section-rdf-in-HTML W3C's RDF/XML Syntax Specification]
|
| proposed

|-
| [[rel-indieauth|micropub]]
| External Resource
| Not allowed
| the micropub endpoint for creating new posts
| [http://indiewebcamp.com/micropub Micropub scecification]
|
| proposed

|-
| [[rel-openid.delegate|openid.delegate]]
| External Resource
| Not allowed
| When the page that contains the link is used as an OpenID indentifier, the relying party perform sOpenID 1.1 authentication with the link target as the identifier instead.
| [http://openid.net/specs/openid-authentication-1_1.html#delegating_authentication OpenID Authentication 1.1]
|
| proposed

|-
| [[rel-openid.server|openid.server]]
| External Resource
| Not allowed
| The OpenID server for the relying party to contact for OpenID 1.1 authentication
| [http://openid.net/specs/openid-authentication-1_1.html#anchor4 OpenID Authentication 1.1]
|
| proposed

|-
| [[rel-openid2.local_id|openid2.local_id]]
| External Resource
| Not allowed
| When the page that contains the link is used as an OpenID indentifier, the relying party perform sOpenID 2.0 authentication with the link target as the identifier instead.
| [http://openid.net/specs/openid-authentication-2_0.html#rfc.section.7.3.3 OpenID Authentication 2.0]
|
| proposed

|-
| [[rel-openid2.provider|openid2.provider]]
| External Resource
| Not allowed
| The OpenID server for the relying party to contact for OpenID 2.0 authentication
| [http://openid.net/specs/openid-authentication-2_0.html#rfc.section.7.3.3 OpenID Authentication 2.0]
|
| proposed

|-
| [[rel-p3pv1|p3pv1]]
| External Resource
| Not allowed
| References a machine-readable privacy policy description in the P3P format
| [http://www.w3.org/TR/P3P/#syntax_link P3P spec]
|
| proposed

|-
| [[rel-pgpkey|pgpkey]]
| External Resource
| Not allowed
| Associates a PGP key with a Web page so that the Web page URL can be used as the commenter's URL in PGP-signed blog comments and the blogging system receiving the comment can fetch the key and verify the signature as belonging to the owner of the URL.
| [http://golem.ph.utexas.edu/~distler/blog/archives/000320.html PGP-Signed Comments]
|
| proposed

|-
| [[rel-pingback|pingback]]
| External Resource
| Not allowed
| gives the address of the pingback server that handles pingbacks to the current document
| [http://www.hixie.ch/specs/pingback/pingback Pingback]
|
| proposed

|-
| [[rel-prerender|prerender]]
| External Resource
| External Resource
| Prerenders the Web page targeted by the link including running it scripts.
| [[rel-prerender]]
|
| proposed

|-
| [[rel-profile|profile]]
| External Resource
| Contextual External Resource
| indicate[s] that the destination of that hyperlink is a metadata profile (e.g. an [[XMDP]] profile) for the current page or portion thereof. See also [[xmdp-brainstorming]].
| [http://microformats.org/wiki/rel-profile rel-profile]
|
| proposed

|-
| [[rel-publisher|publisher]]
| External Resource
| External Resource
| Indicates that the referenced document is a metadata profile (e.g., a social-media/real-name profile such as a Google+ profile) for the publisher of the current page, or some portion of the current page.
| [https://support.google.com/plus/answer/1713826?hl=en Google help page]
|
| proposed

|-
| [[rel-rendition|rendition]]
| External Resource
| External Resource
| Indicates some example rendering, interpretation, or depiction of the source. User agents may choose to execute, display, or render the target in-place; or navigate to the target.
| [http://www.globalmentor.com/specs/html-rel-rendition/ HTML rel rendition]
|
| proposed

|-
| [[rel-reply-to|reply-to]]
| External Resource
| Hyperlink
| indicates any mailbox(es) (i.e. email addresses) to which responses are to be sent. ''Note: this is distinct from the 'in-reply-to' value which refers to the originating document, not to the address where comments should be sent.
| [http://tools.ietf.org/html/rfc2822 RFC2822] (originally [http://tools.ietf.org/html/rfc822#section-4.4.3 RFC822])
|
| ratified

|-
| [[rel-service|service]]
| External Resource
| Not allowed
| Atom Publishing Protocol editing service autodiscovery.
| [http://wiki.whatwg.org/wiki/ServiceRelExtension Documentation on the WHATWG wiki]
|
| proposed

|-
| [[rel-shortlink|shortlink]]
| External Resource
| Not allowed
| Specifies the preferred shortened URL for the page.
| [http://code.google.com/p/shortlink/wiki/Specification shortlink spec]
|
| proposed

|-
| [[rel-sidebar|sidebar]]
| Hyperlink
| Hyperlink
| Indicates that the referenced document is intended to be shown in a secondary browsing context.
| [[rel-sidebar]]
|
| proposed

|-
| [[rel-sitemap|sitemap]]
| External Resource
| Not allowed
| Provides a link to an XML document describing the layout of the site.
| [[rel-sitemap]]
|
| proposed

|-
| [[rel-subresource|subresource]]
| External Resource
| Not allowed
| An external resource intended for use within the current page.
| [http://www.chromium.org/spdy/link-headers-and-server-hint/link-rel-subresource Chromium documentation]
|
| proposed

|-
| [[rel-syndication|syndication]]
| Hyperlink
| Hyperlink
| Refers to a page which is a syndicated copy of the current page.
| [[rel-syndication]]
|
| proposed

|-
| [[rel-timesheet|timesheet]]
| External Resource
| Not allowed
| Applies a timesheet to the document.
| [http://www.w3.org/TR/timesheets/#smilTimesheetsNS-Elements-Timesheet non-normative section in the Timesheet spec]
|
| proposed

|-
| [[rel-token_endpoint|token_endpoint]]
| External Resource
| Not allowed
| Specify an HTTP endpoint that micropub clients can use to obtain an access token given an authorization code
| [http://indiewebcamp.com/token-endpoint token endpoint documentation]
|
| proposed

|-
| [[rel-webmention|webmention]]
| External Resource
| Hyperlink
| gives the address of the webmention endpoint that handles webmentions to the current document
| [http://webmention.org/ WebMention specification]
|
| proposed

|-
| [[rel-widget|widget]]
| External Resource
| External Resource
| Autodiscovery for W3C widgets
| [http://dev.w3.org/2006/waf/widgets/Overview.html#linking-to-a-widget-package-from-a-html- non-normative section in the Widget packaging spec]
|
| proposed

|-
| [[rel-wlwmanifest|wlwmanifest]]
| External Resource
| Not allowed
| Windows Live Writer manifest autodiscovery
| [http://msdn.microsoft.com/en-us/library/bb463263.aspx documentation on MSDN]
|
| proposed

|-
| [[rel-image_src|image_src]]
| External Resource
| Not allowed
| Specify a Webpage Icon for use by Facebook, Yahoo, Digg, etc.
| Unknown, but see for instance [http://www.niallkennedy.com/blog/2009/03/enhanced-social-share.html this]
| probably redundant with rel=icon
| proposed

|-
| [[rel-cmis-acl|http://docs.oasis-open.org/ns/cmis/link/200908/acl]]
| External Resource
| External Resource
| Identifies the resource containing a CMIS ACL document for the link context
| [http://docs.oasis-open.org/cmis/CMIS/v1.0/cs01/cmis-spec-v1.0.html#_Toc243905525 CMIS 1.0, Section 3.4.3.4]
|
| proposed

|-
| [[rel-stylesheet/less|stylesheet/less]]
| External Resource
| Not allowed
| Less CSS framework stylesheets.
| [http://lesscss.org/#-client-side-usage Less CSS usage]
|
| proposed

|}

== brainstorming ==
Several rel values are being brainstormed as potential microformats and are thus listed here. If you find you have a use for such semantics in real world examples, consider trying out these values and provide feedback on the respective brainstorming page(s) with your results and experiences.

You may list new proposed rel values here, and even better if you can list and link to POSH uses in the wild.

{| border="1"
|+
! rel value !! summary !! brainstormed in and usage in the wild

|-
| [[rel-accessibility|accessibility]] || indicate[s] that the destination of that hyperlink contains accessibility information for the current page. || [http://www.brucelawson.co.uk/2009/rel-accessibility/ blog post] which itself uses the rel value in a <link> tag in the head of the document.

|-
| [[rel-author|author]] || indicate[s] that the destination of that hyperlink represents the author of the current page. Combines with [[rel-me|rel-me]] to chain authorship information. || Google has said it will index rel-Author in this [http://googlewebmastercentral.blogspot.com/2011/06/authorship-markup-and-web-search.html blog post], with further [http://www.google.com/support/webmasters/bin/answer.py?answer=1229920 discussion of the rel-me connection] See also [http://dev.w3.org/html5/spec/Overview.html#link-type-author the HTML5 spec]

|-
| [[rel-bibliography|bibliography]] || indicate[s] that the destination of that hyperlink is a bibliography for the current page. || [http://microformats.org/discuss/mail/microformats-discuss/2007-October/010863.html mailing list post, 2007-10-15]

|-
| [[rel-cite|cite]] || indicate[s] that the destination of that hyperlink is an authoritative source or a precedent to the current page. || [[distributed-conversation-brainstorming]]

|-
| [[rel-group|group]] || the referenced document represents a group to which the person represented by the current document belongs || [[group-brainstorming]]

|-
| [[rel-jslicense|jslicense]]
| Refers to a document with JavaScript source code and license information (also called a [http://www.gnu.org/licenses/javascript-labels.html JavaScript License Web Labels] page). We might want choose a keyword for this that is more general -- there are many situations besides JavaScript in which it is desirable or required by license agreements (e.g., GNU GPL) to make an offer of both the source code and a copy of a license when distributing object code versions of a given work.
|* Brainstorming page -- thoughts on the name?
* Ex. [http://www.eff.org EFF.org] (on <code>link</code>)
* Ex. [http://www.fsf.org FSF.org] (on <code>a</code>)
|-
| [[rel-longdesc|longdesc]] || Alternative to the img longdesc attribute, for use on visible links || [http://www.google.com/search?q=rel%3D%22longdesc%22 Google search for rel=longdesc in the wild] shows many sources of proposals. Please edit this to list the earliest and perhaps most recent/comprehensive proposal. No known real world POSH usage in the wild yet.

|-
| [[rel-map|map]] || Link to a map. Possibly embedded within an adr, hCard, geo or hCalendar. Parsers {{may}} attempt to parse the URL if it is a link to a known map site (e.g. Geohash, Google Maps, Multimap) and extract co-ordinates and other useful data. || (to [[User:TobyInk|TobyInk]] by email)

|-
| [[rel-member|member]] || the referenced document represents a member of the group represented by the current document || [[group-brainstorming]]

|-
| [[rel-m_PageScroll2id|m_PageScroll2id]] || JS to scroll to a defined ID || [[group-brainstorming]]

|-
| [[rel-preconnect|preconnect]] || indicates an origin that will be used to fetch required resources. Initiating an early connection, which includes the DNS lookup, TCP handshake, and optional TLS negotiation, allows the user agent to mask the high costs of connection establishment latency.|| [https://igrigorik.github.io/resource-hints/#preconnect resource hints draft]

|-
| [[rel-prefetch|prefetch]] || indicates the URL and content-type of a resource that is likely to be a required resource when the next action or navigation is triggered. Initiating an early fetch allows the user agent to mask the request latency of the resource and make it available sooner to the application.|| [https://igrigorik.github.io/resource-hints/#prefetch resource hints draft]

|-
| [[rel-preload|preload]] || indicates the URL and content-type of a resource that should be fetched as early as possible by the user agent. Initiating an early fetch allows the user agent to mask the request latency of the resource and make it available sooner to the application.|| [https://igrigorik.github.io/resource-hints/#preload resource hints draft]

|-
| [[rel-prerender|prerender]] || indicates the URL of the next navigation target. Initiating a prerender allows the user agent to deliver an instant navigation experience: the user agent downloads the top-level resource and its assets, and performs all of the processing steps required to show the page without actually showing it to the user.|| [https://igrigorik.github.io/resource-hints/#prerender resource hints draft]

|-
| [[rel-profile|profile]] || indicate[s] that the destination of that hyperlink is a metadata profile (e.g. an [[XMDP]] profile) for the current page or portion thereof || [[xmdp-brainstorming]]

|-
| [[rel-shortlink|shortlink]] || the referenced document represents the current document but with a shorter URL || [http://samj.net/2009/04/introducing-relshort-better-alternative.html blog post]
|-
| source || the referenced document represents the source code for the current document or project || [[source-brainstorming]] [http://adactio.com/journal/6667/ blog post]

|-
| vcalendar-parent || link from an event to a containing event || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]
|-
| vcalendar-child || link from an event to a contained event || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]
|-
| vcalendar-sibling || link from an event to a related event with the same container || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]

|-
| [[rel-status|status]] || the referenced document represents the status (or source of status updates) for the author of this document || [http://monkinetic.com/2009/11/24/status-autodiscovery-relstatus.html blog post]

|}

=== more brainstorming ===
See also:
* [[genealogy-brainstorming]] for some thoughts on possible additional values for family relationships (use existing [[XFN]] [[rel-parent|parent]], [[rel-child|child]], [[rel-sibling|sibling]], [[rel-spouse|spouse]], [[rel-kin|kin]] values first though)
* [[xpn-brainstorming]] for some thoughts on possible additional values for professional relationships (use existing [[XFN]] [[rel-co-worker|co-worker]], [[rel-colleague|colleague]] values first though)

== POSH usage ==
There are numerous rel values used as [[POSH]], both in the wild, whose origins are not necessarily known, nor are their meanings consistent. There are also numerous rel values from external proposals of varying degrees of merit. It is useful to document their existence and summarize their implied meanings/usage intent as research that may be used to perhaps take one or more of them thru the microformats [[process]] if there is both sufficient interest and sufficient in the wild usage.

Note: If a value is missing from this table, it may have either already been promoted by writing it up as a proposal, or demoted by being explicitly dropped. Please check the other tables first before adding to this table.

Note: this list is incomplete, please help complete it from the following sources:

External sources:
* [http://developer.mozilla.org/about/meta Meta Information in DevMo Docs] (DevMo)
* [http://wiki.mozilla.org/Microsummaries Microsummary]
* [http://lachy.id.au/dev/markup/specs/wclr/ Web Communication Link Relationships] (WCLR)
* [http://www.w3.org/MarkUp/Relationships.html W3C Link Relationship values draft] (LRdraft) - from a draft of the HTML spec circa 1991.
* [http://www.whatwg.org/specs/web-apps/current-work/multipage/section-links.html#linkTypes HTML5 draft] '''Liable to change'''
* [http://wiki.foaf-project.org/Autodiscovery FOAF Project Wiki: Autodiscovery] (FOAF)
* [http://www.apps.ietf.org/rfc/rfc4685.html RFC4685]
* [http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html Google Blog]

{| border="1"
|+
! rel value !! summary !! origin !! proposal(s)

|-
| [[rel-archive|archive]] || index of archived entries || unknown, perhaps Wordpress open source blogging software || WCLR

|-
| [[rel-archives|archives]] || Provides a link to a collection of records, documents, or other materials of historical interest. || || HTML5

|-
|[[rel-author|author]]||see brainstorming above for suggested use by google||unknown || DevMo / HTML5

|-
| [[rel-canonical|canonical]] || To help search engines disambiguate the same page with multiple representations || Google || [http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html Google]/[http://www.bing.com/community/blogs/webmaster/archive/2009/02/12/partnering-to-help-solve-duplicate-content-issues.aspx Microsoft]/[http://www.ysearchblog.com/2009/02/12/fighting-duplication-adding-more-arrows-to-your-quiver/ Yahoo!], [http://blog.ask.com/2009/02/ask-is-going-canonical.html Ask Jeeves]

|-
| [[rel-comment|comment]] || … || … || WCLR

|-
| [[rel-contribution|contribution]] || … || … || WCLR

|-
| [[rel-edituri|EditURI]]
| Location of the xml-rpc gateway for a Wordpress install that allows external programs to add, edit and delete posts. Used by "[http://codex.wordpress.org/Weblog_Client WordPress blog client]" software for automating posting and updating blog content from your desktop. || Seen in [http://www.wordpress.org/ WordPress], e.g. [http://www.tom-watson.co.uk/]. || Description stubbed in [[rel-edituri]].

|-
| [[rel-endorsed|endorsed]] || … || … || WCLR

|-
| [[rel-fan|fan]] || xxxx. || … || [[hcard-user-profile-authoring]]

|-
| [[rel-feed|feed]] || Gives the address of a syndication feed for the current document. || … || WCLR/ HTML5

|-
| [[rel-footnote|footnote]] || Location of the footnote on a link to a footnote. || Markdown preprocessors such as [http://maruku.rubyforge.org/ Maruku] || HTML5

|-
| [[rel-icon|icon]] || Imports an icon to represent the current document. (Allowed in <code>link</code> only) || [http://dev.w3.org/html5/spec-LC/links.html#rel-icon HTML5] || WCLR/HTML5

|-
| [[rel-kinetic-stylesheet|kinetic-stylesheet]] || Imports a [http://kssproject.org/ KSS] 'kinetic stylesheet' to bind dynamic behavior to elements || Used in the [http://plone.org Plone] Content Management System || …

|-
| [[rel-lightbox|lightbox]] || Hook - Indicates that following the link will trigger a "lightbox" script (Allowed in <code>link</code> only) || ([http://www.google.co.uk/search?q=rel%3D%22lightbox%22 Google search for rel=lightbox in the wild]) || …

|-
| [[rel-lightbox|lightbox[group_name]]] || Used by lightbox scripts to group different sets of images together. Images from one group will not appear in another group's lightbox. See also "lightbox". || [http://lokeshdhakar.com/projects/lightbox2/#how Lightbox 2] || …

|-
| [[rel-prettyPhoto|prettyPhoto]] || See also "lightbox" || ([http://www.google.fr/search?q=rel%3D%22prettyphoto%22 Google search for rel="prettyphoto" in the wild]) || …

|-
| [[rel-clearbox|clearbox]] || See also "lightbox" || ([http://www.google.fr/search?q=rel%3D%22clearbox%22 Google search for rel="clearbox" in the wild]) || …

|-
| [[rel-made|made]] || … || … || LRdraft

|-
| [[rel-meta|meta]] || … || [http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/#transport 1999 W3C RDF syntax REC] || FOAF

|-
| [[rel-microsummary|microsummary]]|| … || … ||[http://wiki.mozilla.org/Microsummaries Microsummary], be aware of: [[page-summary-formats#Issues_2|microsummary issues]]

|-
| [[rel-noreferrer|noreferrer]] || indicates that no referrer information is to be leaked when following the link. || [http://dev.w3.org/html5/spec-LC/links.html#rel-noreferrer HTML5] || HTML5

|-
| [[rel-openid-delegate|openid.delegate]] || … || ([http://www.google.co.uk/search?q=%22rel%3Dopenid%22 Google search for rel=openid.* in the wild]) || …

|-
| [[rel-openid-server|openid.server]] || … || ([http://www.google.co.uk/search?q=%22rel%3Dopenid%22 Google search for rel=openid.* in the wild]) || …

|-
| [[rel-permalink|permalink]] || … || … || WCLR

|-
| [[rel-pgpkey|pgpkey]] || (see also rel-publickey) || … || [http://golem.ph.utexas.edu/~distler/blog/archives/000320.html], [http://golem.ph.utexas.edu/~distler/blog/archives/000325.html]

|-
| [[rel-pingback|pingback]] || Gives the address of the pingback server that handles pingbacks to the current document. (Allowed in <code>link</code> only) || … || WCLR/ HTML5

|-
| [[rel-popover|popover]] || Used by a JS widget to display a large, descriptive tooltip. || [http://twitter.github.com/bootstrap Twitter's Bootstrap] [http://twitter.github.com/bootstrap/javascript.html#popovers Popover.js] || …

|-
| [[rel-prefetch|prefetch]] || Specifies that the target resource should be pre-emptively cached. (Allowed in <code>link</code> only) || … || HTML5

|-
| [[rel-privacy|privacy]] || Specifies that the target resource is the privacy policy. || … || …

|-
| [[rel-publickey|publickey]] || (see also rel-pgpkey) || … || [http://rasterweb.net/raster/2002/12/12/20021212072812/]

|-
| [[rel-referral|referral]] || … || … || WCLR

|-
| [[rel-related|related]] || … || … || WCLR

|-
| [[rel-replies|replies]] || indicates a continued thread || unknown || [http://www.apps.ietf.org/rfc/rfc4685.html RFC4685]

|-
| [[rel-resource|resource]] || … || … || WCLR

|-
| [[rel-search|search]] || … || unknown || unknown

|-
| [[rel-sitemap|sitemap]] || Links to a site map document. || … || http://www.sitemaps.org/

|-
| [[rel-sponsor|sponsor]] || … || … || WCLR

|-
| [[rel-tooltip|tooltip]] || Used by a JS widget to display a tooltip similar (though more customizable) to what is shown by browsers if the 'title' attribute is present. || [http://twitter.github.com/bootstrap Twitter's Bootstrap] [http://twitter.github.com/bootstrap/javascript.html#tooltips Tooltip.js] (and likely other JS tools) || …

|-
| [[rel-trackback|trackback]] || … || unknown, perhaps open source Movable Type blogging software || WCLR

|-
| [[rel-unendorsed|unendorsed]] || (probably redundant to [[rel-nofollow|nofollow]]) || … || WCLR

|-
| [[rel-user|user]] || … || … || WCLR
|-
| [[rel-wlwmanifest|wlwmanifest]] || Used by "[http://explore.live.com/windows-live-writer Windows Live Writer]," a Microsoft [http://codex.wordpress.org/Weblog_Client blog client] for automating posting and updating blog content from your desktop. || Seen in [http://www.wordpress.org/ WordPress], e.g. [http://www.tom-watson.co.uk/]. Similar values are probably used by other blog content management systems as well. || …

|}

=== WCLR ===

The WCLR proposal is described by its author (in e-mail, 2007-09-25) as:

<blockquote>
…now effectively obsolete, since HTML5 and Microformats cover all the worthwhile relationships in that already.

These are [http://www.whatwg.org/specs/web-apps/current-work/multipage/section-links.html#linkTypes covered by HTML5 already]:

* permalink -> bookmark
* archive -> archives
* feed
* pingback
* unendorsed -> nofollow

The rest now seem unnecessary.
</blockquote>

Nonetheless, there may be some mileage in using them in microformats, at least until HTML5 is widely available.

== Dublin Core ==
In the past, Dublin Core values have been added to this page in the table about HTML5 features, but no examples, nor an actual specification explicitly stating how the value(s) should be used in HTML could be found. The linked specifications below have been updated so we should start considering Dublin Core values accordingly.

{| border="1"
|+
! rel value !! summary !! source
|-
| schema.DC || a specification of all metadata terms maintained by the Dublin Core Metadata Initiative, with regard to the fifteen terms of the Dublin Core Metadata Element Set already published || [http://www.dublincore.org/documents/dcq-html/ Dublin Core]

|-
| schema.DCTERMS || a specification of all metadata terms maintained by the Dublin Core Metadata Initiative, reflecting the changes described more fully in the 2012 document "Maintenance changes to DCMI Metadata Terms" [http://dublincore.org/usage/decisions/2012/dcterms-changes/] || [http://www.dublincore.org/documents/dcq-html/ Dublin Core]
|-
|}

'''Issues need updating given new information from linked resources.'''

Notes:
* Dublin Core. This search may help: [http://www.google.co.uk/search?as_q=rel%3Dschema.*&hl=en&num=10&btnG=Google+Search&as_epq=&as_oq=&as_eq=&lr=&as_ft=i&as_filetype=&as_qdr=all&as_occt=any&as_dt=i&as_sitesearch=http%3A%2F%2Fdublincore.org&as_rights=&safe=images].
** '''examples from that search only use invisible <code><link href></code> element'''. At first glance it appears the results from the search show only uses with the invisible <code><link href></code> element which is not ideal for content relationships. Content relationships should be user visible and thus uses with <code><a href></code> are strongly preferred.
*** [http://www.ietf.org/rfc/rfc2731.txt RFC2731] defines <code>rel="schema.AC"</code> and <code>rel="schema.RC"</code> with the pattern <code>rel="schema.PREFIX"</code> as a syntax for defining namespaces for use in meta[@name], *[@rel], *[@rev] and (as per eRDF) *[@class] attributes. A link to a Dublin Core metadata schema is generally not suitable for end users, so <code><link href></code> appears to be more appropriate than <code><a href></code> for those that use Dublin Core metadata schemas.
*** The scheme proposed above provides metadata namespace declarations. As described by DCMI specifications, such indications '''cannot''' be provided w/o a suitable namespace. In order to give complete pieces of information, the correct description set must be: <code><link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"></code> (for the namespace declaration, followed by) <code><meta name="DCTERMS.<nowiki>[element]</nowiki>" content="<nowiki>[element.value]</nowiki>"></code> for related elements.
**** Note: [http://purl.org/dc/terms/ schema.DCTERMS] is conventionally related to an upgraded elements list than [http://purl.org/dc/elements/1.1/ schema.DC] and should be preferred as rel values. Both are discussed here for subject completeness)
** '''proposal to use in content currently only theoretical'''. Thus unfortunately the use of Dublin Core in user visible content like <code><a href></code> appears to be strictly theoretical. See [http://microformats.org/discuss/mail/microformats-discuss/2008-January/011445.html microformats-discuss/2008-January/011445.html] for a proposal to use Dublin Core in user visible content.
*** '''recent improvements'''. DCMI solves some trouble concerning metadata through the ''description set model''. Some of these informations cannot currently be provided in any standard ways other than DC, namely dates, validity and periodicity. Following this public bug report ([https://www.w3.org/Bugs/Public/show_bug.cgi?format=multiple&id=22520]), the correct namespace declaration for DC and DCTERMS metadata are now considered valid HTML code. We '''must''' encourage this practice both for internal usefulness and for shared practices.

* The Dublin Core document [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] is a specification for, and gives examples of, both <link rel="schema.DC" href="http://purl.org/dc/elements/1.1/"> and <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/">. Note that Dublin Core encourages the use of DCTERMS elements over DC. A list of projects which use Dublin Core metadata is maintained [http://dublincore.org/projects/ here].
* [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] also includes examples of <link rel="DCTERMS.[element]" href="">, where [element] = subject, isReferencedBy, creator, and publisher. The <link> tag is used instead of the <meta> tag whenever the content is a URL. (Note that this use is different from, but related to, <link rel="schema.DCTERMS" href="">.) Potentially, ''any'' of the 55 DCTERMS elements could be used in this way, and this could include use in HTML 5.
** As said before, HTML5 validators now allow the use of <code><link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"></code> for namespace declarations.

== Use with HTTP Link Header ==
You can also use any of the rel values (that are allowed for link elements) with HTTP Link Headers,

Example: returning a Javascript file with a license (since JS itself has no way to indicate a license)
<source lang=text>
Link: <http://creativecommons.org/publicdomain/zero/1.0/>; rel="license"
</source>

For multiple licenses (e.g. CC-SA and GPL), simply use multiple <code>Link:</code> headers.
<source lang=text>
Link: <http://creativecommons.org/licenses/by-sa/3.0/>; rel="license"
Link: <http://www.gnu.org/licenses/gpl.html>; rel="license"
</source>

Example: similarly, linking to a copyright statement for an image:
<source lang=text>
Link: <http://example.org/copyright.html>; rel="copyright"
</source>
or providing a brief inline copyright statement:
<source lang=text>
Link: <data:text/plain;charset=utf-8,Copyright 2013 ExampleCo, All Rights Reserved.>; rel="copyright"
</source>

== unspecified ==
Some rel values have been added to this page perhaps in one of the tables above, but no examples, nor an actual specification explicitly stating that the value(s) should be used in the HTML 'rel' attribute could be found. They are listed here in the hopes someone can discover more specific/precise URLs to examples or specifications about them (preferably both). Until such precise URLs to examples/specs are provided, the values can be treated as they are purely theoretical and thus of little interest.

A simple list here is sufficient.

== non HTML rel values ==
There are markup languages other than HTML that also have a rel attribute, often based upon the HTML rel attribute.
It is useful to document some of these other languages and their rel values for both reference purposes, and to provide background research for the possible development and re-use of these values in HTML, as [[poshformats]] or [[microformats]]

Sources:
* [[Atom]] [[RFC4287]] specification.
* See http://www.iana.org/assignments/link-relations.html for more.
* See [http://amundsen.com/media-types/maze/format/#link-relations Maze+XML]
* See [http://amundsen.com/media-types/collection/format/#link-relations Collection+JSON]
* See [http://www.opensearch.org/Specifications/OpenSearch/1.1#Url_rel_values OpenSearch]
* See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

{| border="1"
|+
! rel value !! summary (from the relevant specification where possible)) !! defining specification

|-
| self
| From http://www.ietf.org/rfc/rfc4287.txt : <blockquote>The value "self" signifies that the IRI in the value of the href attribute identifies a resource equivalent to the containing element.</blockquote>
| [[Atom]] http://www.ietf.org/rfc/rfc4287.txt

|-
| http://gdata.youtube.com/schemas/2007#in-reply-to || See http://code.google.com/apis/youtube/2.0/developers_guide_protocol_comments.html || YouTube extension to Atom

|-
| collection || Refers to a resource which represents a collection of which the current resource is a member.

When used in the Maze+XML media type, the associated URI returns the available collection of mazes.
|| Maze+XML, Collection+JSON, OpenSearch

|-
| east || Refers to a resource to the "east" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the east in the active maze.

|| Maze+XML

|-
| exit || Refers to a resource that represents the exit or end of the current client actvity or process.

When used in the Maze+XML media type, the associated URI points to the final exit resource of the active maze.

|| Maze+XML

|-
| north || Refers to a resource that is "north" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the north in the active maze.

|| Maze+XML

|-
| south || Refers to a resource that is "south" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the south in the active maze.

|| Maze+XML

|-
| [[rel-via|via]] || Identifies a resource that is the source of the information in the context. || Atom 1.0 Syndication format (RFC 4287)

|-
| west || Refers to a resource that is "west" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the west in the active maze.

|| Maze+XML

|-
| item || The target IRI points to a resource that is a member of a collection represented by the context IRI. || Collection+JSON

|-
| create-form || When included in a resource, the "create-form" link relation MAY identify a target resource that represents the form to append a new member to the link context. || See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

|-
| edit-form || When included in a resource, the "edit-form" link relation identifies a target resource that represents the form for editing associated resource. || See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

|-
| lightframe || Opens the target in a lightbox. On inclusion it provides a simple target the lightframe and loads the content in a lightbox effect || Lightbox

|-
| superbox[image] || jQuery Superbox! is a script which allows you display windows with the lightbox effect. || superbox

|-
| wp-video-lightbox || wp-video-lightbox! is a rel to anchor tag script display videos with the lightbox effect. || wp-video-lightbox

|-
| youtube || Opens the target youtube video in using the Swipebox Plugin || Swipebox

|-
| shadowbox || shadowbox is a jQuery script for images displaying with the "lightbox" effects. || shadowbox

|-
| permission || When included in a resource, the "permission" link relation MAY identify a target resource that represents the list of entities that can access or modify the resource in the link context. || See [http://cdoc.io/spec.html#permission-link-relation Collection Document Media Type Specification]

|-
| version-history
| When included on a versioned resource, this link points to a resource containing the version history for this resource.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| latest-version
| When included on a versioned resource, this link points to a resource containing the latest (e.g., current) version.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| working-copy
| When included on a versioned resource, this link points to a working copy for this resource.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| working-copy-of
| When included on a working copy, this link points to the versioned resource from which this working copy was obtained.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| predecessor-version
| When included on a versioned resource, this link points to a resource containing the predecessor version in the version history.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| successor-version
| When included on a versioned resource, this link points to a resource containing the successor version in the version history.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| ... || ... || ...

|}

== dropped ==
The following rel values were in earlier version(s) of specification(s) and it is presumed by their absence from the most recent version of the respective specification(s) that they have been deprecated or obsoleted.

In general, you {{should not}} use any dropped values.

If any such values have been superceded by standard values (see the first table on this page), then you {{must not}} use the dropped versions.

In particular:
* if a rel value was in a draft and is missing (without explanation) from the final spec, or
* if a rel value was in a previous version of and is missing (without explanation) from an update to the specification (even a draft update)

Then absent any other information or explanation, it is presumed that the group/editors working on that specification decided to explicitly drop it (either in development, or in the updated version) and thus it should be obsoleted (not re-registered).

If you wish to add them, please research why such values were omitted from latter specifications before doing so. If you do discover the reasoning, please add a short statement or link to thereof into the appropriate place in the following table.

If there is more data, e.g. a link to an email of discussion of the spec development that explains ''why'' the rel value was dropped, and it explicitly states, e.g. it was without prejudice, or merely post-poned, or perhaps expected to be spun-out into its spec (or some other explicit positive reason), then it makes to link/cite that explicit text as part of a proposal.

Sources:
* [http://www.w3.org/MarkUp/html3/ HTML3] (HTML3) / has been superceded by [http://www.w3.org/MarkUp/Wilbur/ HTML 3.2] - which itself has been superceded by [http://www.w3.org/TR/REC-html40 HTML 4.0] - which itself has been updated by [http://w3.org/TR/html401 HTML 4.01], commonly referred to as "HTML 4" in this wiki and other places.)
* [http://www.w3.org/TR/relations.html Proposed HTML 4.0 link types] (HTML4dropped) - obsoleted/superceded by the HTML 4.0 Recommendation. Any values that were in the "Proposed HTML 4.0 link types" document but didn't make it into the HTML 4.0 Recommendation were thus explicitly dropped and should be avoided.

{| border="1"
|+
! rel value !! summary !! defining specification !! why dropped

|-
|[[rel-banner|banner]]||Was used to reference another document to be used as banner for this document (i.e. a form of "include" statement).|| HTML3 ||unknown

|-
| [[rel-begin|begin]] || identifies the author-defined start of a sequence of documents of which the current document is a node.
|| HTML4dropped||unknown

|-
| [[rel-biblioentry|biblioentry]] || identifies a bibliographic entry || HTML4dropped||unknown

|-
| [[rel-bibliography|bibliography]] || identifies a bibliography || HTML4dropped||unknown

|-
| [[rel-child|child]] (obsolete/superceded) || the target document is a hierarchical child, or subdocument, of the current document|| HTML4dropped||unknown

|-
| [[rel-citation|citation]] || the target is a bibliographic citation || HTML4dropped||unknown

|-
| [[rel-collection|collection]] || the target document is an collection that contains the current document || HTML4dropped||unknown

|-
| [[rel-definition|definition]] || identifies a definition of a term || HTML4dropped||unknown

|-
| [[rel-disclaimer|disclaimer]] || identifies a hypertext link to a legal disclaimer || HTML4dropped||unknown

|-
| [[rel-editor|editor]] || identifies a hypertext link to an editor || HTML4dropped||unknown

|-
| [[rel-end|end]] || identifies the author-defined end of a sequence of documents of which the current document is a node. || HTML4dropped||unknown

|-
| [[rel-footnote|footnote]] || the anchor is a footnote marker and the target is a footnote || HTML4dropped||unknown

|-
| [[rel-navigate|navigate]] || the target document contains information such as a image map that will help users to gain a sense of how and where to found information || HTML4dropped||unknown

|-
| [[rel-origin|origin]] || synonym for <code>top</code> || HTML4dropped||unknown

|-
| [[rel-parent|parent]] (obsolete/superceded) || the target document is the hierarchical parent, or container, of the current document|| HTML4dropped||unknown

|-
| [[rel-pointer|pointer]] || the target is a pointer to the real target. This value can be used by a user agent to perform a pre-fetch of the specified target for evaluation until the real target is reached || HTML4dropped||unknown

|-
| [[rel-publisher|publisher]] || identifies a hypertext link to a publisher || HTML4dropped||unknown

|-
| [[rel-sibling|sibling]] (obsolete/superceded) || the target document is a child of a common parent, or a hierarchical peer of the current document|| HTML4dropped||unknown

|-
| [[rel-top|top]] || the target document is the logical top node of the tree (see also <code>begin</code>) || HTML4dropped||unknown

|-
| [[rel-trademark|trademark]] || identifies a hypertext link to a trademark notice || HTML4dropped||unknown

|-
| [[rel-translation|translation]] || the target is a translation to another language || HTML4dropped||unknown

|-
| [[rel-urc|urc]] || identifies a Universal Resource Citation || HTML4dropped||unknown

|-
|}

== dropped without prejudice ==
In one known instance (from HTML4 to HTML5), some rel values were in an earlier version of a specification (or a proposal) and were dropped from a latter (draft) version, and it was noted that these values were dropped with the intent that they could still be proposed in a registry and thus they explicitly were not deprecated or obsoleted. This section documents such values as separate from the [[#dropped|dropped]] section.

In general, you {{should not}} use any dropped values.

If any such values have been superceded by standard values (see the first table on this page), then you {{must not}} use the dropped versions.

Rel values that were dropped without prejudice from a specification will be considered similar to new values that have never been specified.

If you know of additional rel values that were dropped without prejudice from an update to a specification, please cite a URL and quote from the group developing the specification that officially states from that group that the dropping of the values was done without prejudice, or equivalent statement (such as explicit allowance of external registration, proposal, and/or development).

This table serves a historical purpose. If you wish to propose a value from this table, please copy it and leave it in place.

Sources:
* Several rel values were [http://www.w3.org/Bugs/Public/show_bug.cgi?id=7475#c15 explicitly dropped from HTML5]. Per: [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Issue 118 Decision] ('''emphasis''' added): <blockquote>"The final proposal argues for the removal of some relation values, to wit, it suggests removal of '''index, up, first and last'''. It was pointed out in survey comments that these relations are already registered in the IANA link relation registry. Presumably, '''these relations could also be entered in whatever other registry or registries HTML5 adopts for this purpose'''...."Next Steps..."Since the relations to be removed are already registered at the IANA link relation registry, no further action is needed to include them there. WG members are '''free to register or record these relations elsehwere''' [sic], as well."</blockquote>

{| border="1"
|+
! rel value
! summary
! defining specification
! why dropped

|-
| [[rel-first|first]]
| synonym for <code>begin</code>
| HTML4dropped - never in an official spec
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-index|index]]
| Refers to a document providing an index for the current document.
| was in [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-last|last]]
| synonym for <code>end</code>
| HTML4dropped - never in an official spec
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-up|up]]
|When the document forms part of a hierarchy, this link references the immediate parent of the current document.
| was in [http://www.w3.org/MarkUp/html3/dochead.html HTML3] - but [http://www.w3.org/TR/html401/types.html#type-links dropped in HTML4]
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
|}

See related [http://dev.w3.org/html5/spec/links.html#linkTypes HTML5: Link types] for existing HTML5 specified rel values.

== rejected ==
Some rel values have been proposed and rejected. They are listed here to make that explicit. Authors {{must not}} use rejected rel values.

Source: [[rejected-formats]].

{| border="1"
|+
! rel value !! origin / proposal !! why rejected
|-
| [[rel-logo|logo]]
| [http://relogo.org Relogo.org]
| [[rejected-formats#Logo]]
|-
|[[rel-pavatar|pavatar]] || [http://pavatar.com/ pavatar] || [[rejected-formats#Pavatar]]
|-
|}

== tools ==
See [[implementations]].

== addtional external research ==
Here are some additional historical references to the development or rel-values which may be useful when researching values, especially why specific values may have been proposed but abandoned.
* 1996-06-07 [http://www.w3.org/MarkUp/draft-ietf-html-relrev-00.txt Hypertext links in HTML] (copies: [http://ftp.ics.uci.edu/pub/ietf/html/draft-ietf-html-relrev-00.txt ftp.ics.uci.edu])
* 1996-11-13 [http://www.w3.org/Architecture/NOTE-link Describing and Linking Web Resources]
* 1997-01-23 [http://lists.gnu.org/archive/html/lynx-dev/1997-01/msg00537.html LYNX-DEV Lynx and the LINK tag]
* 1997-01-24 [http://lists.w3.org/Archives/Public/w3c-sgml-wg/1997Jan/0357.html Taxonomy list]
* 1997-03-28 [http://www.w3.org/TR/WD-htmllink-970328 W3C Working Draft: Hypertext Links and Meta Information in HTML]

=== previous attempts at documenting ===
There have been previous attempts at documenting known rel values, most of which fell out of date due to being dependent on a single author maintaining them. They're listed here purely for historical reasons, and are not sufficient to be references of their own (since they're just individual curations of other references)
* [http://fantasai.tripod.com/qref/Appendix/LinkTypes/ltdef.html Link Type Definitions Glossary] by fantasai
* ...

== related ==
{{rel-related-pages}}
* [[elemental-microformats]]
* [[existing-rev-values]]
* [[existing-class-names]]

== copyright ==

{{cc-pd-license}}

existing-rel-values

2015-03-11T15:53:24Z

Andy sky: Undo revision 64849 by Andy sky (Talk): missing footnotes template

<entry-title> existing rel values </entry-title>

This page contains tables of known HTML rel values from specifications, formats, proposals, brainstorms, and non-trivial [[POSH]] usage in the wild. In addition, dropped and rejected values are listed at the end for comprehensiveness.

usage: see [[rel-faq#How_is_rel_used|how is 'rel' used]]. Regarding rev, see: [[rel-faq#Should_rev_even_be_used|should 'rev' even be used]].

This page is also the official rel registry ([http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#other-link-types][http://www.w3.org/TR/html5/links.html#other-link-types]). Add new and proposed rel values to the following section:
* [[existing-rel-values#HTML5_link_type_extensions|HTML5 link type extension]]

== formats ==
These rel values are defined formats from specifications (HTML 4, microformats) are thus are recommended for general use. Alphabetically ordered by value.

Note:
* Do not add proposed rel values for HTML5 here, add them to the [[#HTML5_link_type_extensions|HTML5 link type extensions]] table.
* Do not add rel values you find in the wild to this table of rel formats, instead add them to the table in the [[existing-rel-values#POSH_usage|POSH section]].
* Do not add non-HTML rel values you find to this table of rel formats, instead add them to the table in the [[existing-rel-values#non_HTML_rel_values|non HTML rel values section]].
* Do not add rel values from obsolete/superceded proposals or drafts, instead add them to the table in the "dropped" section.

Sources:
* W3C Recommendations:
** [http://www.w3.org/TR/html401/types.html#h-6.12 HTML 4.01 section 6.12 Link types] (HTML4 Link types)
** [http://www.w3.org/TR/grddl/ Gleaning Resource Descriptions from Dialects of Languages] (GRDDL)
* [[microformats]] specifications
** [[xfn]]
** [[rel-license]]
** [[rel-nofollow]]

{| border="1"
|+
! Keyword
! Effect on <code>link</code>
! Effect on <code>a</code>, <code>area</code>
! Brief description (from the relevant specification where possible)
! Link to defining specification

|-
| [[rel-acquaintance|acquaintance]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be an acquaintance
| [[XFN]]

|-
| [[rel-alternate|alternate]]
| external resource
| external relation
| Designates substitute versions for the document in which the link occurs. When used together with the <code>lang</code> attribute, it implies a translated version of the document. When used together with the <code>media</code> attribute, it implies a version designed for a different medium (or media).
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-appendix|appendix]]
| allowed
| allowed
| Refers to a document serving as an appendix in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-bookmark|bookmark]]
| not allowed
| allowed
| Refers to a bookmark. A bookmark is a link to a key entry point within an extended document. The <code>title</code> attribute may be used, for example, to label the bookmark. Note that several bookmarks may be defined in each document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-chapter|chapter]]
| allowed
| allowed
| Refers to a document serving as a chapter in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-child|child]]
| not allowed
| external relation
| the referenced person is a child of the person represented by the current document
| [[XFN]]

|-
| [[rel-colleague|colleague]]
| not allowed
| external relation
| the referenced person is a colleague of the person represented by the current document
| [[XFN]]

|-
| [[rel-contact|contact]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be a contact
| [[XFN]]

|-
| [[rel-contents|contents]]
| allowed
| allowed
| Refers to a document serving as a table of contents. Some user agents also support the synonym ToC (from "Table of Contents").
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-copyright|copyright]]
| allowed
| allowed
| Refers to a copyright statement for the current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-co-resident|co-resident]]
| not allowed
| external relation
| the referenced person lives in the same residence as the person represented by the current document
| [[XFN]]

|-
| [[rel-co-worker|co-worker]]
| not allowed
| external relation
| the referenced person is a co-worker of the person represented by the current document
| [[XFN]]

|-
| [[rel-crush|crush]]
| not allowed
| external relation
| this person considers the referenced person to be a crush (i.e. has a crush on the referenced person)
| [[XFN]]

|-
| [[rel-date|date]]
| not allowed
| external relation
| this person considers the referenced person to be a date (i.e. is dating the referenced person)
| [[XFN]]

|-
| [[rel-friend|friend]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be a friend
| [[XFN]]

|-
| [[rel-glossary|glossary]]
| allowed
| allowed
| Refers to a document providing a list of terms and their definitions that pertain to the current document.||[http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-help|help]]
| allowed
| allowed
| Refers to a document offering help (more information, links to other sources information, etc.)
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-its-rules|its-rules]]
| allowed
| not allowed
| Refers to a document with external ITS rules.
| [http://www.w3.org/TR/its20/#selection-global-html5 Internationalization Tag Set (ITS) Version 2.0]

|-
| [[rel-kin|kin]]
| not allowed
| external relation
| the referenced person is part of the extended family of the person represented by the current document
| [[XFN]]

|-
| [[rel-license|license]]
| allowed
| allowed
| …indicates that the <nowiki>[referenced document]</nowiki> is a license for the current page.
| [[rel-license]]

|-
| [[rel-me|me]]
| external relation
| external relation
| the referenced document represents the same person as does the current document
| [[XFN]]

|-
| [[rel-met|met]]
| not allowed
| external relation
| this person has met the referenced person
| [[XFN]]

|-
| [[rel-muse|muse]]
| not allowed
| external relation
| the referenced person inspires the person represented by the current document
| [[XFN]]

|-
| [[rel-neighbor|neighbor]]
| not allowed
| external relation
| the referenced person lives nearby the person represented by the current document
| [[XFN]]

|-
| [[rel-next|next]]
| external relation
| external relation
| Refers to the next document in a linear sequence of documents. User agents may choose to preload the "next" document, to reduce the perceived load time.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-nofollow|nofollow]]
| not allowed
| external relation
| indicates that the destination of that hyperlink {{should-not}} be afforded any additional weight or ranking by user agents which perform link analysis upon web pages (e.g. search engines).
| [[rel-nofollow]]

|-
| [[rel-parent|parent]]
| not allowed
| external relation
| the referenced person is a parent of the person represented by the current document
| [[XFN]]

|-
| [[rel-prev|prev]]
| external relation
| external relation
| Refers to the previous document in an ordered series of documents. Some user agents also support the synonym "Previous".
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-previous|previous]]
| external relation
| external relation
| Synonym of <code>prev</code>
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-section|section]]
| allowed
| allowed
| Refers to a document serving as a section in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-sibling|sibling]]
| not allowed
| external relation
| the referenced person is a sibling of the person represented by the current document
| [[XFN]]

|-
| [[rel-spouse|spouse]]
| not allowed
| external relation
| the referenced person is a spouse of the person represented by the current document
| [[XFN]]

|-
| [[rel-start|start]]
| allowed
| allowed
| Refers to the first document in a collection of documents. This link type tells search engines which document is considered by the author to be the starting point of the collection.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-stylesheet|stylesheet]]
| external resource
| not allowed
| a style sheet for the current document used with the invisible <link href> element which is not ideal for content relationships. Content relationships should be user visible and thus uses with <a href> are strongly preferred. Unfortunately the use of stylesheet in user visible content like <a href> appears to be strictly theoretical.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-subsection|subsection]]
| allowed
| allowed
| Refers to a document serving as a subsection in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-sweetheart|sweetheart]]
| not allowed
| external relation
| this person considers the referenced person to be their sweetheart
| [[XFN]]

|-
| [[rel-tag|tag]]
| not allowed
| allowed
| …indicates that the <nowiki>[referenced document]</nowiki> is an author-designated "tag" (or keyword/subject) for the current page.
| [[rel-tag]]

|-
| [[rel-toc|toc]]
| allowed
| allowed
| Synonym of <code>contents</code> (from "Table Of Contents")
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-transformation|transformation]]
| allowed
| allowed
| Relates a source document to a transformation, usually represented in XSLT, that relates the source document syntax to the RDF graph syntax. Used in [[grddl|GRDDL]]
| [http://www.w3.org/TR/grddl/#transformation GRDDL]

|}

=== notes ===
*<code>rel="alternate"</code> can take further meaning from additional attributes, such as
** <code>rel="alternate" lang="fr"</code> (French language version of this page)
** <code>rel="alternate" media="print"</code> (printable version of this page)
** <code>rel="alternate" media="handheld"</code> (version of the page intended or better for handheld/portable devices like PDAs, cell phones, etc.)

*Synonyms such as "previous", "toc" are not as widely supported as the main term.

== proposals ==
A few rel values have been developed as drafts as a result of going through most of the microformats [[process]], and are thus listed here for your serious consideration. You may use these values, and if you find any problems with them please point them out on the respective "issues" page for the rel value.

{| border="1"
|+
! rel value !! summary !! proposed in !! external spec (if any)
|-
| [[rel-pronunciation|pronunciation]] || …indicates that the destination of the 'link' element is a document providing a pronunciation lexicon for speech-synthesis purposes. || [[rel-pronunciation]]
|-
| [[rel-directory|directory]] || …indicates that the destination of the hyperlink is a directory listing containing an entry for the current page. || [[rel-directory]]
|-
| [[rel-enclosure|enclosure]] || …indicates that the destination of that hyperlink is intended to be downloaded and cached. || [[rel-enclosure]] || [http://www.apps.ietf.org/rfc/rfc4287.html RFC4287]
|-
| [[rel-home|home]] || …indicates that the <nowiki>[referenced document]</nowiki> is the homepage of the site in which the current page appears. || [[rel-home]]
|-
| [[rel-payment|payment]] || …indicates that the destination of the hyperlink provides a way to show or give support (e.g. financial) for the current page|| [[rel-payment]]
|}

== HTML5 link type extensions ==

The following values are registered as link type extensions per the [http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#other-link-types requirements in the WHATWG HTML spec] and the [http://dev.w3.org/html5/spec/links.html#other-link-types requirements in the W3C HTML5 spec].

Before you register a new value:
* '''Please check the [[#formats|Formats table]] and DO NOT re-register''' rel values that are already there. Please note that the W3C HTML WG has made a [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Decision] to drop <code>index</code>, <code>up</code>, <code>first</code> and <code>last</code> from the HTML5 spec itself.
* '''Please check the [[#dropped|Dropped table]] and DO NOT register''' values that are already there. If you believe a rel value was dropped from another specification without prejudice, please provide link/cite to explicit text/decision stating as such, e.g. the value was merely postponed, or perhaps expected to be spun-out into its own spec from the group developing that specification.

Note that entries in the [[#formats|Formats table]] and entries that are already in HTML5 as built-in keywords are also considered extensions with the "Ratified" status.

Please make sure that registrations added here have all the required data filled in ''including'':
* "Effect on link"
* "Effect on a and area" and
* a link to a spec that documents the keyword ''as an HTML <code>rel</code> keyword''. (A spec that merely defines the file format of the link target but does not define the <code>rel</code> keyword for use in HTML is not the kind of spec that is being required here.)

Entries lacking any of the above required data will likely be removed.

Changes to this registry will not be reflected in validators in real time. But validators will typically get automatically updated with the changes within one week or so

{| border="1"
|+
! Keyword
! Effect on <code>link</code>
! Effect on <code>a</code>, <code>area</code>
! Brief description
! Link to specification
! Synonyms
! Status

|-
| [[rel-apple-touch-icon|apple-touch-icon]]
| External Resource
| Not allowed
| Specify a Webpage Icon for a “Web Clip”, or “touch icon”, for mobile devices (not limited to Apple devices).
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| probably redundant with rel=icon
| proposed

|-
| [[rel-apple-touch-icon-precomposed|apple-touch-icon-precomposed]]
| External Resource
| Not allowed
| Specify a Webpage Icon for a “Web Clip”, or “touch icon”, for mobile devices (not limited to Apple devices).
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| probably redundant with rel=icon
| proposed

|-
| [[rel-apple-touch-startup-image|apple-touch-startup-image]]
| External Resource
| Not allowed
| Specify a splashscreen for Web apps on iOS Safari
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| maybe redundant with rel=icon with the sizes attribute?
| proposed

|-
| [[rel-attachment|attachment]]
| Hyperlink
| Hyperlink
| The resource linked to is "attached" to this document, similar to email attachments. Used in WordPress.
| No formal specification
|
| proposed

|-
| [[WPVL_PRETTYPHOTO_REL]]
| Hyperlink
| Hyperlink
| Open lightbox with video
| No formal specification
|
| proposed

|-
| [[rel-authorization_endpoint|authorization_endpoint]]
| External Resource
| Not allowed
| Specify a hosted authorization server
| [http://indiewebcamp.com/distributed-indieauth distributed IndieAuth documentation]
|
| proposed

|-
| [[rel-canonical|canonical]]
| External Resource
| Not allowed
| Specifies the canonical URL for the current document in order to help avoid duplicate content.
| [http://en.wikipedia.org/wiki/Canonical_meta_tag Canonical meta tag] [http://www.Google.com/support/webmasters/bin/answer.py?answer=139066#2 Canonicalization at Google Webmaster Central] [http://www.Bing.com/community/site_blogs/b/webmaster/archive/2009/02/12/partnering-to-help-solve-duplicate-content-issues.aspx Microsoft Webmaster Center] [http://www.YSearchBlog.com/2009/02/12/fighting-duplication-adding-more-arrows-to-your-quiver/ Yahoo! Search Blog]
|
| proposed

|-
| [[rel-category|category]]
| Hyperlink
| Hyperlink
| Refers to a category assigned to the current document or post. Implemented by WordPress for indicating a relation between a blog post and a category.
| [[rel-category]]
|
| proposed

|-
| [[rel-component|component]]
| External Resource
| Not allowed
| Specify an HTML document that is treated as a component of this document.
| [https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/components/index.html Web Components]
|
| proposed

|-
| [[rel-chrome-webstore-item|chrome-webstore-item]]
| External Resource
| Not allowed
| Link tag to declare for app and extensions inline installations hosted in the Chrome Web Store.
| [https://developers.google.com/chrome/web-store/docs/inline_installation Using Inline Installation]
|
| proposed

|-
| [[rel-disclosure|disclosure]]
| Not allowed
| External Resource
| The 'disclosure' Link Relation Type designates a list of patent disclosures or a particular patent disclosure itself made with respect to material for which such relation type is specified.
| [http://tools.ietf.org/html/draft-yevstifeyev-disclosure-relation The 'disclosure' Link Relation Type]
|
| proposed

|-
| [[rel-discussion|discussion]]
| Hyperlink
| Hyperlink
| Refers to discussion of the current document or post.
| [[rel-discussion]]
|
| proposed

|-
| [[rel-dns-prefetch|dns-prefetch]]
| External Resource
| Not allowed
| Tells the browser to perform dns lookup for host names ahead of use.
| [https://developer.mozilla.org/En/Controlling_DNS_prefetching Mozilla documentation] [http://dev.chromium.org/developers/design-documents/dns-prefetching Google documentation]
|
| proposed

|-
| [[rel-edit|edit]]
| Hyperlink
| Not allowed
| Tells the browser where the current page can be edited
| [http://universaleditbutton.org/Registered_MIME_type#Alternate_Linking_Scheme Universal Edit Button Alternate Linking Scheme]. Implemented in at least [http://mediawiki.org MediaWiki].
|
| proposed

|-
| [[rel-edituri|EditURI]]
| External Resource
| Not allowed
| A blogging auto discovery value, commonly used by WordPress
| [http://bitworking.org/projects/atom/draft-gregorio-09.html#Edit AtomAPI]
|
| proposed

|-
| [[rel-enclosure|enclosure]]
| External Resource
| External Resource
| Indicates that the referred resource is intended to be downloaded and cached.
| [[rel-enclosure]]
|
| proposed

|-
| [[rel-entry-content|entry-content]]
| Not allowed
| External Resource
| Indicates that the referenced document is an alternative display source for an Internet Explorer Web Slice.
| [http://msdn.microsoft.com/en-us/library/cc304073(VS.85).aspx#_alternative Web Slice format specification 0.9]
|
| proposed

|-
| [[rel-external|external]]
| Not allowed
| Hyperlink
| Indicates that the referenced document is not part of the same site as the current document.
| [[rel-external]]
|
| proposed

|-
| [[rel-home|home]]
| Hyperlink
| Hyperlink
| Refers to the top level document for the current document. It can be combined with 'alternate' to indicate a feed for the site of the current page.
| [[rel-home]]
|
| proposed

|-
| [[rel-hub|hub]]
| Hyperlink
| Hyperlink
| Refers to a hub that enables registration for notification of updates to the current page.
| [http://pubsubhubbub.googlecode.com/svn/trunk/pubsubhubbub-core-0.3.html#discovery PubSubHubbub Spec]
|
| proposed

|-
| [[rel-in-reply-to|in-reply-to]]
| Hyperlink
| Hyperlink
| Refers to an original post that the current page is a comment on or reply to.
| [[rel-in-reply-to]]
|
| proposed

|-
| [[rel-index|index]]
| Hyperlink
| Hyperlink
| Refers to a document providing a list of topics with pointers that pertain to the current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
|
| proposed

|-
| [[rel-indieauth|indieauth]]
| External Resource
| Not allowed
| the IndieAuth server for the relying party to contact for IndieAuth authentication
| [http://spec.indieauth.com/ IndieAuth specification]
|
| proposed

|-
| [[rel-issues|issues]]
| Hyperlink
| Hyperlink
| Refers to issues regarding the current document or specification.
| [[rel-discussion]]
|
| proposed

|-
| [[rel-lightbox|lightbox]]
| Not allowed
| Img Pop-Up
| Images with this attribute are displayed in a larger way than embedded in a website (or how you specified it) when clicked (e.g. with installed "Lightbox 2"-Plugin). When adding [group] to rel="lightbox" all images get a clickable button for next/prev; insert into <code><a rel="lightbox[group]"><img src="http:example.com/img.jpg"></a></code>
| [http://lokeshdhakar.com/projects/lightbox2/ Lightbox 2] (needs actual specification to be kept in this list, this link is just documentation of one implementation)
|
| proposed

|-
| [[rel-manifest|manifest]]
| External Resource
| Not allowed
| Imports or links to a manifest
| [http://w3c.github.io/manifest/#linking W3C Manifest for web application]
|
| proposed

|-
| [[rel-meta|meta]]
| External Resource
| Not allowed
| External metadata about the HTML document
| [http://www.w3.org/TR/2004/REC-rdf-syntax-grammar-20040210/#section-rdf-in-HTML W3C's RDF/XML Syntax Specification]
|
| proposed

|-
| [[rel-indieauth|micropub]]
| External Resource
| Not allowed
| the micropub endpoint for creating new posts
| [http://indiewebcamp.com/micropub Micropub scecification]
|
| proposed

|-
| [[rel-openid.delegate|openid.delegate]]
| External Resource
| Not allowed
| When the page that contains the link is used as an OpenID indentifier, the relying party perform sOpenID 1.1 authentication with the link target as the identifier instead.
| [http://openid.net/specs/openid-authentication-1_1.html#delegating_authentication OpenID Authentication 1.1]
|
| proposed

|-
| [[rel-openid.server|openid.server]]
| External Resource
| Not allowed
| The OpenID server for the relying party to contact for OpenID 1.1 authentication
| [http://openid.net/specs/openid-authentication-1_1.html#anchor4 OpenID Authentication 1.1]
|
| proposed

|-
| [[rel-openid2.local_id|openid2.local_id]]
| External Resource
| Not allowed
| When the page that contains the link is used as an OpenID indentifier, the relying party perform sOpenID 2.0 authentication with the link target as the identifier instead.
| [http://openid.net/specs/openid-authentication-2_0.html#rfc.section.7.3.3 OpenID Authentication 2.0]
|
| proposed

|-
| [[rel-openid2.provider|openid2.provider]]
| External Resource
| Not allowed
| The OpenID server for the relying party to contact for OpenID 2.0 authentication
| [http://openid.net/specs/openid-authentication-2_0.html#rfc.section.7.3.3 OpenID Authentication 2.0]
|
| proposed

|-
| [[rel-p3pv1|p3pv1]]
| External Resource
| Not allowed
| References a machine-readable privacy policy description in the P3P format
| [http://www.w3.org/TR/P3P/#syntax_link P3P spec]
|
| proposed

|-
| [[rel-pgpkey|pgpkey]]
| External Resource
| Not allowed
| Associates a PGP key with a Web page so that the Web page URL can be used as the commenter's URL in PGP-signed blog comments and the blogging system receiving the comment can fetch the key and verify the signature as belonging to the owner of the URL.
| [http://golem.ph.utexas.edu/~distler/blog/archives/000320.html PGP-Signed Comments]
|
| proposed

|-
| [[rel-pingback|pingback]]
| External Resource
| Not allowed
| gives the address of the pingback server that handles pingbacks to the current document
| [http://www.hixie.ch/specs/pingback/pingback Pingback]
|
| proposed

|-
| [[rel-prerender|prerender]]
| External Resource
| External Resource
| Prerenders the Web page targeted by the link including running it scripts.
| [[rel-prerender]]
|
| proposed

|-
| [[rel-profile|profile]]
| External Resource
| Contextual External Resource
| indicate[s] that the destination of that hyperlink is a metadata profile (e.g. an [[XMDP]] profile) for the current page or portion thereof. See also [[xmdp-brainstorming]].
| [http://microformats.org/wiki/rel-profile rel-profile]
|
| proposed

|-
| [[rel-publisher|publisher]]
| External Resource
| External Resource
| Indicates that the referenced document is a metadata profile (e.g., a social-media/real-name profile such as a Google+ profile) for the publisher of the current page, or some portion of the current page.
| [https://support.google.com/plus/answer/1713826?hl=en Google help page]
|
| proposed

|-
| [[rel-rendition|rendition]]
| External Resource
| External Resource
| Indicates some example rendering, interpretation, or depiction of the source. User agents may choose to execute, display, or render the target in-place; or navigate to the target.
| [http://www.globalmentor.com/specs/html-rel-rendition/ HTML rel rendition]
|
| proposed

|-
| [[rel-reply-to|reply-to]]
| External Resource
| Hyperlink
| indicates any mailbox(es) (i.e. email addresses) to which responses are to be sent. ''Note: this is distinct from the 'in-reply-to' value which refers to the originating document, not to the address where comments should be sent.
| [http://tools.ietf.org/html/rfc2822 RFC2822] (originally [http://tools.ietf.org/html/rfc822#section-4.4.3 RFC822])
|
| ratified

|-
| [[rel-service|service]]
| External Resource
| Not allowed
| Atom Publishing Protocol editing service autodiscovery.
| [http://wiki.whatwg.org/wiki/ServiceRelExtension Documentation on the WHATWG wiki]
|
| proposed

|-
| [[rel-shortlink|shortlink]]
| External Resource
| Not allowed
| Specifies the preferred shortened URL for the page.
| [http://code.google.com/p/shortlink/wiki/Specification shortlink spec]
|
| proposed

|-
| [[rel-sidebar|sidebar]]
| Hyperlink
| Hyperlink
| Indicates that the referenced document is intended to be shown in a secondary browsing context.
| [[rel-sidebar]]
|
| proposed

|-
| [[rel-sitemap|sitemap]]
| External Resource
| Not allowed
| Provides a link to an XML document describing the layout of the site.
| [[rel-sitemap]]
|
| proposed

|-
| [[rel-subresource|subresource]]
| External Resource
| Not allowed
| An external resource intended for use within the current page.
| [http://www.chromium.org/spdy/link-headers-and-server-hint/link-rel-subresource Chromium documentation]
|
| proposed

|-
| [[rel-syndication|syndication]]
| Hyperlink
| Hyperlink
| Refers to a page which is a syndicated copy of the current page.
| [[rel-syndication]]
|
| proposed

|-
| [[rel-timesheet|timesheet]]
| External Resource
| Not allowed
| Applies a timesheet to the document.
| [http://www.w3.org/TR/timesheets/#smilTimesheetsNS-Elements-Timesheet non-normative section in the Timesheet spec]
|
| proposed

|-
| [[rel-token_endpoint|token_endpoint]]
| External Resource
| Not allowed
| Specify an HTTP endpoint that micropub clients can use to obtain an access token given an authorization code
| [http://indiewebcamp.com/token-endpoint token endpoint documentation]
|
| proposed

|-
| [[rel-webmention|webmention]]
| External Resource
| Hyperlink
| gives the address of the webmention endpoint that handles webmentions to the current document
| [http://webmention.org/ WebMention specification]
|
| proposed

|-
| [[rel-widget|widget]]
| External Resource
| External Resource
| Autodiscovery for W3C widgets
| [http://dev.w3.org/2006/waf/widgets/Overview.html#linking-to-a-widget-package-from-a-html- non-normative section in the Widget packaging spec]
|
| proposed

|-
| [[rel-wlwmanifest|wlwmanifest]]
| External Resource
| Not allowed
| Windows Live Writer manifest autodiscovery
| [http://msdn.microsoft.com/en-us/library/bb463263.aspx documentation on MSDN]
|
| proposed

|-
| [[rel-image_src|image_src]]
| External Resource
| Not allowed
| Specify a Webpage Icon for use by Facebook, Yahoo, Digg, etc.
| Unknown, but see for instance [http://www.niallkennedy.com/blog/2009/03/enhanced-social-share.html this]
| probably redundant with rel=icon
| proposed

|-
| [[rel-cmis-acl|http://docs.oasis-open.org/ns/cmis/link/200908/acl]]
| External Resource
| External Resource
| Identifies the resource containing a CMIS ACL document for the link context
| [http://docs.oasis-open.org/cmis/CMIS/v1.0/cs01/cmis-spec-v1.0.html#_Toc243905525 CMIS 1.0, Section 3.4.3.4]
|
| proposed

|-
| [[rel-stylesheet/less|stylesheet/less]]
| External Resource
| Not allowed
| Less CSS framework stylesheets.
| [http://lesscss.org/#-client-side-usage Less CSS usage]
|
| proposed

|}

== brainstorming ==
Several rel values are being brainstormed as potential microformats and are thus listed here. If you find you have a use for such semantics in real world examples, consider trying out these values and provide feedback on the respective brainstorming page(s) with your results and experiences.

You may list new proposed rel values here, and even better if you can list and link to POSH uses in the wild.

{| border="1"
|+
! rel value !! summary !! brainstormed in and usage in the wild

|-
| [[rel-accessibility|accessibility]] || indicate[s] that the destination of that hyperlink contains accessibility information for the current page. || [http://www.brucelawson.co.uk/2009/rel-accessibility/ blog post] which itself uses the rel value in a <link> tag in the head of the document.

|-
| [[rel-author|author]] || indicate[s] that the destination of that hyperlink represents the author of the current page. Combines with [[rel-me|rel-me]] to chain authorship information. || Google has said it will index rel-Author in this [http://googlewebmastercentral.blogspot.com/2011/06/authorship-markup-and-web-search.html blog post], with further [http://www.google.com/support/webmasters/bin/answer.py?answer=1229920 discussion of the rel-me connection] See also [http://dev.w3.org/html5/spec/Overview.html#link-type-author the HTML5 spec]

|-
| [[rel-bibliography|bibliography]] || indicate[s] that the destination of that hyperlink is a bibliography for the current page. || [http://microformats.org/discuss/mail/microformats-discuss/2007-October/010863.html mailing list post, 2007-10-15]

|-
| [[rel-cite|cite]] || indicate[s] that the destination of that hyperlink is an authoritative source or a precedent to the current page. || [[distributed-conversation-brainstorming]]

|-
| [[rel-group|group]] || the referenced document represents a group to which the person represented by the current document belongs || [[group-brainstorming]]

|-
| [[rel-jslicense|jslicense]]
| Refers to a document with JavaScript source code and license information (also called a [http://www.gnu.org/licenses/javascript-labels.html JavaScript License Web Labels] page). We might want choose a keyword for this that is more general -- there are many situations besides JavaScript in which it is desirable or required by license agreements (e.g., GNU GPL) to make an offer of both the source code and a copy of a license when distributing object code versions of a given work.
|* Brainstorming page -- thoughts on the name?
* Ex. [http://www.eff.org EFF.org] (on <code>link</code>)
* Ex. [http://www.fsf.org FSF.org] (on <code>a</code>)
|-
| [[rel-longdesc|longdesc]] || Alternative to the img longdesc attribute, for use on visible links || [http://www.google.com/search?q=rel%3D%22longdesc%22 Google search for rel=longdesc in the wild] shows many sources of proposals. Please edit this to list the earliest and perhaps most recent/comprehensive proposal. No known real world POSH usage in the wild yet.

|-
| [[rel-map|map]] || Link to a map. Possibly embedded within an adr, hCard, geo or hCalendar. Parsers {{may}} attempt to parse the URL if it is a link to a known map site (e.g. Geohash, Google Maps, Multimap) and extract co-ordinates and other useful data. || (to [[User:TobyInk|TobyInk]] by email)

|-
| [[rel-member|member]] || the referenced document represents a member of the group represented by the current document || [[group-brainstorming]]

|-
| [[rel-m_PageScroll2id|m_PageScroll2id]] || JS to scroll to a defined ID || [[group-brainstorming]]

|-
| [[rel-preconnect|preconnect]] || indicates an origin that will be used to fetch required resources. Initiating an early connection, which includes the DNS lookup, TCP handshake, and optional TLS negotiation, allows the user agent to mask the high costs of connection establishment latency.|| [https://igrigorik.github.io/resource-hints/#preconnect resource hints draft]

|-
| [[rel-prefetch|prefetch]] || indicates the URL and content-type of a resource that is likely to be a required resource when the next action or navigation is triggered. Initiating an early fetch allows the user agent to mask the request latency of the resource and make it available sooner to the application.|| [https://igrigorik.github.io/resource-hints/#prefetch resource hints draft]

|-
| [[rel-preload|preload]] || indicates the URL and content-type of a resource that should be fetched as early as possible by the user agent. Initiating an early fetch allows the user agent to mask the request latency of the resource and make it available sooner to the application.|| [https://igrigorik.github.io/resource-hints/#preload resource hints draft]

|-
| [[rel-prerender|prerender]] || indicates the URL of the next navigation target. Initiating a prerender allows the user agent to deliver an instant navigation experience: the user agent downloads the top-level resource and its assets, and performs all of the processing steps required to show the page without actually showing it to the user.|| [https://igrigorik.github.io/resource-hints/#prerender resource hints draft]

|-
| [[rel-profile|profile]] || indicate[s] that the destination of that hyperlink is a metadata profile (e.g. an [[XMDP]] profile) for the current page or portion thereof || [[xmdp-brainstorming]]

|-
| [[rel-shortlink|shortlink]] || the referenced document represents the current document but with a shorter URL || [http://samj.net/2009/04/introducing-relshort-better-alternative.html blog post]
|-
| source || the referenced document represents the source code for the current document or project || [[source-brainstorming]] [http://adactio.com/journal/6667/ blog post]

|-
| vcalendar-parent || link from an event to a containing event || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]
|-
| vcalendar-child || link from an event to a contained event || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]
|-
| vcalendar-sibling || link from an event to a related event with the same container || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]

|-
| [[rel-status|status]] || the referenced document represents the status (or source of status updates) for the author of this document || [http://monkinetic.com/2009/11/24/status-autodiscovery-relstatus.html blog post]

|}

=== more brainstorming ===
See also:
* [[genealogy-brainstorming]] for some thoughts on possible additional values for family relationships (use existing [[XFN]] [[rel-parent|parent]], [[rel-child|child]], [[rel-sibling|sibling]], [[rel-spouse|spouse]], [[rel-kin|kin]] values first though)
* [[xpn-brainstorming]] for some thoughts on possible additional values for professional relationships (use existing [[XFN]] [[rel-co-worker|co-worker]], [[rel-colleague|colleague]] values first though)

== POSH usage ==
There are numerous rel values used as [[POSH]], both in the wild, whose origins are not necessarily known, nor are their meanings consistent. There are also numerous rel values from external proposals of varying degrees of merit. It is useful to document their existence and summarize their implied meanings/usage intent as research that may be used to perhaps take one or more of them thru the microformats [[process]] if there is both sufficient interest and sufficient in the wild usage.

Note: If a value is missing from this table, it may have either already been promoted by writing it up as a proposal, or demoted by being explicitly dropped. Please check the other tables first before adding to this table.

Note: this list is incomplete, please help complete it from the following sources:

External sources:
* [http://developer.mozilla.org/about/meta Meta Information in DevMo Docs] (DevMo)
* [http://wiki.mozilla.org/Microsummaries Microsummary]
* [http://lachy.id.au/dev/markup/specs/wclr/ Web Communication Link Relationships] (WCLR)
* [http://www.w3.org/MarkUp/Relationships.html W3C Link Relationship values draft] (LRdraft) - from a draft of the HTML spec circa 1991.
* [http://www.whatwg.org/specs/web-apps/current-work/multipage/section-links.html#linkTypes HTML5 draft] '''Liable to change'''
* [http://wiki.foaf-project.org/Autodiscovery FOAF Project Wiki: Autodiscovery] (FOAF)
* [http://www.apps.ietf.org/rfc/rfc4685.html RFC4685]
* [http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html Google Blog]

{| border="1"
|+
! rel value !! summary !! origin !! proposal(s)

|-
| [[rel-archive|archive]] || index of archived entries || unknown, perhaps Wordpress open source blogging software || WCLR

|-
| [[rel-archives|archives]] || Provides a link to a collection of records, documents, or other materials of historical interest. || || HTML5

|-
|[[rel-author|author]]||see brainstorming above for suggested use by google||unknown || DevMo / HTML5

|-
| [[rel-canonical|canonical]] || To help search engines disambiguate the same page with multiple representations || Google || [http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html Google]/[http://www.bing.com/community/blogs/webmaster/archive/2009/02/12/partnering-to-help-solve-duplicate-content-issues.aspx Microsoft]/[http://www.ysearchblog.com/2009/02/12/fighting-duplication-adding-more-arrows-to-your-quiver/ Yahoo!], [http://blog.ask.com/2009/02/ask-is-going-canonical.html Ask Jeeves]

|-
| [[rel-comment|comment]] || … || … || WCLR

|-
| [[rel-contribution|contribution]] || … || … || WCLR

|-
| [[rel-edituri|EditURI]]
| Location of the xml-rpc gateway for a Wordpress install that allows external programs to add, edit and delete posts. Used by "[http://codex.wordpress.org/Weblog_Client WordPress blog client]" software for automating posting and updating blog content from your desktop. || Seen in [http://www.wordpress.org/ WordPress], e.g. [http://www.tom-watson.co.uk/]. || Description stubbed in [[rel-edituri]].

|-
| [[rel-endorsed|endorsed]] || … || … || WCLR

|-
| [[rel-fan|fan]] || xxxx. || … || [[hcard-user-profile-authoring]]

|-
| [[rel-feed|feed]] || Gives the address of a syndication feed for the current document. || … || WCLR/ HTML5

|-
| [[rel-footnote|footnote]] || Location of the footnote on a link to a footnote. || Markdown preprocessors such as [http://maruku.rubyforge.org/ Maruku] || HTML5

|-
| [[rel-icon|icon]] || Imports an icon to represent the current document. (Allowed in <code>link</code> only) || [http://dev.w3.org/html5/spec-LC/links.html#rel-icon HTML5] || WCLR/HTML5

|-
| [[rel-kinetic-stylesheet|kinetic-stylesheet]] || Imports a [http://kssproject.org/ KSS] 'kinetic stylesheet' to bind dynamic behavior to elements || Used in the [http://plone.org Plone] Content Management System || …

|-
| [[rel-lightbox|lightbox]] || Hook - Indicates that following the link will trigger a "lightbox" script (Allowed in <code>link</code> only) || ([http://www.google.co.uk/search?q=rel%3D%22lightbox%22 Google search for rel=lightbox in the wild]) || …

|-
| [[rel-lightbox|lightbox[group_name]]] || Used by lightbox scripts to group different sets of images together. Images from one group will not appear in another group's lightbox. See also "lightbox". || [http://lokeshdhakar.com/projects/lightbox2/#how Lightbox 2] || …

|-
| [[rel-prettyPhoto|prettyPhoto]] || See also "lightbox" || ([http://www.google.fr/search?q=rel%3D%22prettyphoto%22 Google search for rel="prettyphoto" in the wild]) || …

|-
| [[rel-clearbox|clearbox]] || See also "lightbox" || ([http://www.google.fr/search?q=rel%3D%22clearbox%22 Google search for rel="clearbox" in the wild]) || …

|-
| [[rel-made|made]] || … || … || LRdraft

|-
| [[rel-meta|meta]] || … || [http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/#transport 1999 W3C RDF syntax REC] || FOAF

|-
| [[rel-microsummary|microsummary]]|| … || … ||[http://wiki.mozilla.org/Microsummaries Microsummary], be aware of: [[page-summary-formats#Issues_2|microsummary issues]]

|-
| [[rel-noreferrer|noreferrer]] || indicates that no referrer information is to be leaked when following the link. || [http://dev.w3.org/html5/spec-LC/links.html#rel-noreferrer HTML5] || HTML5

|-
| [[rel-openid-delegate|openid.delegate]] || … || ([http://www.google.co.uk/search?q=%22rel%3Dopenid%22 Google search for rel=openid.* in the wild]) || …

|-
| [[rel-openid-server|openid.server]] || … || ([http://www.google.co.uk/search?q=%22rel%3Dopenid%22 Google search for rel=openid.* in the wild]) || …

|-
| [[rel-permalink|permalink]] || … || … || WCLR

|-
| [[rel-pgpkey|pgpkey]] || (see also rel-publickey) || … || [http://golem.ph.utexas.edu/~distler/blog/archives/000320.html], [http://golem.ph.utexas.edu/~distler/blog/archives/000325.html]

|-
| [[rel-pingback|pingback]] || Gives the address of the pingback server that handles pingbacks to the current document. (Allowed in <code>link</code> only) || … || WCLR/ HTML5

|-
| [[rel-popover|popover]] || Used by a JS widget to display a large, descriptive tooltip. || [http://twitter.github.com/bootstrap Twitter's Bootstrap] [http://twitter.github.com/bootstrap/javascript.html#popovers Popover.js] || …

|-
| [[rel-prefetch|prefetch]] || Specifies that the target resource should be pre-emptively cached. (Allowed in <code>link</code> only) || … || HTML5

|-
| [[rel-privacy|privacy]] || Specifies that the target resource is the privacy policy. || … || …

|-
| [[rel-publickey|publickey]] || (see also rel-pgpkey) || … || [http://rasterweb.net/raster/2002/12/12/20021212072812/]

|-
| [[rel-referral|referral]] || … || … || WCLR

|-
| [[rel-related|related]] || … || … || WCLR

|-
| [[rel-replies|replies]] || indicates a continued thread || unknown || [http://www.apps.ietf.org/rfc/rfc4685.html RFC4685]

|-
| [[rel-resource|resource]] || … || … || WCLR

|-
| [[rel-search|search]] || … || unknown || unknown

|-
| [[rel-sitemap|sitemap]] || Links to a site map document. || … || http://www.sitemaps.org/

|-
| [[rel-sponsor|sponsor]] || … || … || WCLR

|-
| [[rel-tooltip|tooltip]] || Used by a JS widget to display a tooltip similar (though more customizable) to what is shown by browsers if the 'title' attribute is present. || [http://twitter.github.com/bootstrap Twitter's Bootstrap] [http://twitter.github.com/bootstrap/javascript.html#tooltips Tooltip.js] (and likely other JS tools) || …

|-
| [[rel-trackback|trackback]] || … || unknown, perhaps open source Movable Type blogging software || WCLR

|-
| [[rel-unendorsed|unendorsed]] || (probably redundant to [[rel-nofollow|nofollow]]) || … || WCLR

|-
| [[rel-user|user]] || … || … || WCLR
|-
| [[rel-wlwmanifest|wlwmanifest]] || Used by "[http://explore.live.com/windows-live-writer Windows Live Writer]," a Microsoft [http://codex.wordpress.org/Weblog_Client blog client] for automating posting and updating blog content from your desktop. || Seen in [http://www.wordpress.org/ WordPress], e.g. [http://www.tom-watson.co.uk/]. Similar values are probably used by other blog content management systems as well. || …

|}

=== WCLR ===

The WCLR proposal is described by its author (in e-mail, 2007-09-25) as:

<blockquote>
…now effectively obsolete, since HTML5 and Microformats cover all the worthwhile relationships in that already.

These are [http://www.whatwg.org/specs/web-apps/current-work/multipage/section-links.html#linkTypes covered by HTML5 already]:

* permalink -> bookmark
* archive -> archives
* feed
* pingback
* unendorsed -> nofollow

The rest now seem unnecessary.
</blockquote>

Nonetheless, there may be some mileage in using them in microformats, at least until HTML5 is widely available.

== Dublin Core ==
In the past, Dublin Core values have been added to this page in the table about HTML5 features, but no examples, nor an actual specification explicitly stating how the value(s) should be used in HTML could be found. The linked specifications below have been updated so we should start considering Dublin Core values accordingly.

{| border="1"
|+
! rel value !! summary !! source
|-
| schema.DC || a specification of all metadata terms maintained by the Dublin Core Metadata Initiative, with regard to the fifteen terms of the Dublin Core Metadata Element Set already published || [http://www.dublincore.org/documents/dcq-html/ Dublin Core]

|-
| schema.DCTERMS || a specification of all metadata terms maintained by the Dublin Core Metadata Initiative, reflecting the changes described more fully in the 2012 document "Maintenance changes to DCMI Metadata Terms" [http://dublincore.org/usage/decisions/2012/dcterms-changes/] || [http://www.dublincore.org/documents/dcq-html/ Dublin Core]
|-
|}

'''Issues need updating given new information from linked resources.'''

Notes:
* Dublin Core. This search may help: [http://www.google.co.uk/search?as_q=rel%3Dschema.*&hl=en&num=10&btnG=Google+Search&as_epq=&as_oq=&as_eq=&lr=&as_ft=i&as_filetype=&as_qdr=all&as_occt=any&as_dt=i&as_sitesearch=http%3A%2F%2Fdublincore.org&as_rights=&safe=images].
** '''examples from that search only use invisible <code><link href></code> element'''. At first glance it appears the results from the search show only uses with the invisible <code><link href></code> element which is not ideal for content relationships. Content relationships should be user visible and thus uses with <code><a href></code> are strongly preferred.
*** [http://www.ietf.org/rfc/rfc2731.txt RFC2731] defines <code>rel="schema.AC"</code> and <code>rel="schema.RC"</code> with the pattern <code>rel="schema.PREFIX"</code> as a syntax for defining namespaces for use in meta[@name], *[@rel], *[@rev] and (as per eRDF) *[@class] attributes. A link to a Dublin Core metadata schema is generally not suitable for end users, so <code><link href></code> appears to be more appropriate than <code><a href></code> for those that use Dublin Core metadata schemas.
*** The scheme proposed above provides metadata namespace declarations. As described by DCMI specifications, such indications '''cannot''' be provided w/o a suitable namespace. In order to give complete pieces of information, the correct description set must be: <code><link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"></code> (for the namespace declaration, followed by) <code><meta name="DCTERMS.<nowiki>[element]</nowiki>" content="<nowiki>[element.value]</nowiki>"></code> for related elements.
**** Note: [http://purl.org/dc/terms/ schema.DCTERMS] is conventionally related to an upgraded elements list than [http://purl.org/dc/elements/1.1/ schema.DC] and should be preferred as rel values. Both are discussed here for subject completeness)
** '''proposal to use in content currently only theoretical'''. Thus unfortunately the use of Dublin Core in user visible content like <code><a href></code> appears to be strictly theoretical. See [http://microformats.org/discuss/mail/microformats-discuss/2008-January/011445.html microformats-discuss/2008-January/011445.html] for a proposal to use Dublin Core in user visible content.
*** '''recent improvements'''. DCMI solves some trouble concerning metadata through the ''description set model''. Some of these informations cannot currently be provided in any standard ways other than DC, namely dates, validity and periodicity. Following this public bug report ([https://www.w3.org/Bugs/Public/show_bug.cgi?format=multiple&id=22520]), the correct namespace declaration for DC and DCTERMS metadata are now considered valid HTML code. We '''must''' encourage this practice both for internal usefulness and for shared practices.

* The Dublin Core document [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] is a specification for, and gives examples of, both <link rel="schema.DC" href="http://purl.org/dc/elements/1.1/"> and <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/">. Note that Dublin Core encourages the use of DCTERMS elements over DC. A list of projects which use Dublin Core metadata is maintained [http://dublincore.org/projects/ here].
* [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] also includes examples of <link rel="DCTERMS.[element]" href="">, where [element] = subject, isReferencedBy, creator, and publisher. The <link> tag is used instead of the <meta> tag whenever the content is a URL. (Note that this use is different from, but related to, <link rel="schema.DCTERMS" href="">.) Potentially, ''any'' of the 55 DCTERMS elements could be used in this way, and this could include use in HTML 5.
** As said before, HTML5 validators now allow the use of <code><link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"></code> for namespace declarations.

== Use with HTTP Link Header ==
You can also use any of the rel values (that are allowed for link elements) with HTTP Link Headers,

Example: returning a Javascript file with a license (since JS itself has no way to indicate a license)
<source lang=text>
Link: <http://creativecommons.org/publicdomain/zero/1.0/>; rel="license"
</source>

For multiple licenses (e.g. CC-SA and GPL), simply use multiple <code>Link:</code> headers.
<source lang=text>
Link: <http://creativecommons.org/licenses/by-sa/3.0/>; rel="license"
Link: <http://www.gnu.org/licenses/gpl.html>; rel="license"
</source>

Example: similarly, linking to a copyright statement for an image:
<source lang=text>
Link: <http://example.org/copyright.html>; rel="copyright"
</source>
or providing a brief inline copyright statement:
<source lang=text>
Link: <data:text/plain;charset=utf-8,Copyright 2013 ExampleCo, All Rights Reserved.>; rel="copyright"
</source>

== unspecified ==
Some rel values have been added to this page perhaps in one of the tables above, but no examples, nor an actual specification explicitly stating that the value(s) should be used in the HTML 'rel' attribute could be found. They are listed here in the hopes someone can discover more specific/precise URLs to examples or specifications about them (preferably both). Until such precise URLs to examples/specs are provided, the values can be treated as they are purely theoretical and thus of little interest.

A simple list here is sufficient.

== non HTML rel values ==
There are markup languages other than HTML that also have a rel attribute, often based upon the HTML rel attribute.
It is useful to document some of these other languages and their rel values for both reference purposes, and to provide background research for the possible development and re-use of these values in HTML, as [[poshformats]] or [[microformats]]

Sources:
* [[Atom]] [[RFC4287]] specification.
* See http://www.iana.org/assignments/link-relations.html for more.
* See [http://amundsen.com/media-types/maze/format/#link-relations Maze+XML]
* See [http://amundsen.com/media-types/collection/format/#link-relations Collection+JSON]
* See [http://www.opensearch.org/Specifications/OpenSearch/1.1#Url_rel_values OpenSearch]
* See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

{| border="1"
|+
! rel value !! summary (from the relevant specification where possible)) !! defining specification

|-
| self
| From http://www.ietf.org/rfc/rfc4287.txt : <blockquote>The value "self" signifies that the IRI in the value of the href attribute identifies a resource equivalent to the containing element.</blockquote>
| [[Atom]] http://www.ietf.org/rfc/rfc4287.txt

|-
| http://gdata.youtube.com/schemas/2007#in-reply-to || See http://code.google.com/apis/youtube/2.0/developers_guide_protocol_comments.html || YouTube extension to Atom

|-
| collection || Refers to a resource which represents a collection of which the current resource is a member.

When used in the Maze+XML media type, the associated URI returns the available collection of mazes.
|| Maze+XML, Collection+JSON, OpenSearch

|-
| east || Refers to a resource to the "east" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the east in the active maze.

|| Maze+XML

|-
| exit || Refers to a resource that represents the exit or end of the current client actvity or process.

When used in the Maze+XML media type, the associated URI points to the final exit resource of the active maze.

|| Maze+XML

|-
| north || Refers to a resource that is "north" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the north in the active maze.

|| Maze+XML

|-
| south || Refers to a resource that is "south" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the south in the active maze.

|| Maze+XML

|-
| [[rel-via|via]] || Identifies a resource that is the source of the information in the context. || Atom 1.0 Syndication format (RFC 4287)

|-
| west || Refers to a resource that is "west" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the west in the active maze.

|| Maze+XML

|-
| item || The target IRI points to a resource that is a member of a collection represented by the context IRI. || Collection+JSON

|-
| create-form || When included in a resource, the "create-form" link relation MAY identify a target resource that represents the form to append a new member to the link context. || See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

|-
| edit-form || When included in a resource, the "edit-form" link relation identifies a target resource that represents the form for editing associated resource. || See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

|-
| lightframe || Opens the target in a lightbox. On inclusion it provides a simple target the lightframe and loads the content in a lightbox effect || Lightbox

|-
| superbox[image] || jQuery Superbox! is a script which allows you display windows with the lightbox effect. || superbox

|-
| wp-video-lightbox || wp-video-lightbox! is a rel to anchor tag script display videos with the lightbox effect. || wp-video-lightbox

|-
| youtube || Opens the target youtube video in using the Swipebox Plugin || Swipebox

|-
| shadowbox || shadowbox is a jQuery script for images displaying with the "lightbox" effects. || shadowbox

|-
| permission || When included in a resource, the "permission" link relation MAY identify a target resource that represents the list of entities that can access or modify the resource in the link context. || See [http://cdoc.io/spec.html#permission-link-relation Collection Document Media Type Specification]

|-
| version-history
| When included on a versioned resource, this link points to a resource containing the version history for this resource.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| latest-version
| When included on a versioned resource, this link points to a resource containing the latest (e.g., current) version.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| working-copy
| When included on a versioned resource, this link points to a working copy for this resource.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| working-copy-of
| When included on a working copy, this link points to the versioned resource from which this working copy was obtained.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| predecessor-version
| When included on a versioned resource, this link points to a resource containing the predecessor version in the version history.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| successor-version
| When included on a versioned resource, this link points to a resource containing the successor version in the version history.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| ... || ... || ...

|}

== dropped ==
The following rel values were in earlier version(s) of specification(s) and it is presumed by their absence from the most recent version of the respective specification(s) that they have been deprecated or obsoleted.

In general, you {{should not}} use any dropped values.

If any such values have been superceded by standard values (see the first table on this page), then you {{must not}} use the dropped versions.

In particular:
* if a rel value was in a draft and is missing (without explanation) from the final spec, or
* if a rel value was in a previous version of and is missing (without explanation) from an update to the specification (even a draft update)

Then absent any other information or explanation, it is presumed that the group/editors working on that specification decided to explicitly drop it (either in development, or in the updated version) and thus it should be obsoleted (not re-registered).

If you wish to add them, please research why such values were omitted from latter specifications before doing so. If you do discover the reasoning, please add a short statement or link to thereof into the appropriate place in the following table.

If there is more data, e.g. a link to an email of discussion of the spec development that explains ''why'' the rel value was dropped, and it explicitly states, e.g. it was without prejudice, or merely post-poned, or perhaps expected to be spun-out into its spec (or some other explicit positive reason), then it makes to link/cite that explicit text as part of a proposal.

Sources:
* [http://www.w3.org/MarkUp/html3/ HTML3] (HTML3) / has been superceded by [http://www.w3.org/MarkUp/Wilbur/ HTML 3.2] - which itself has been superceded by [http://www.w3.org/TR/REC-html40 HTML 4.0] - which itself has been updated by [http://w3.org/TR/html401 HTML 4.01], commonly referred to as "HTML 4" in this wiki and other places.)
* [http://www.w3.org/TR/relations.html Proposed HTML 4.0 link types] (HTML4dropped) - obsoleted/superceded by the HTML 4.0 Recommendation. Any values that were in the "Proposed HTML 4.0 link types" document but didn't make it into the HTML 4.0 Recommendation were thus explicitly dropped and should be avoided.

{| border="1"
|+
! rel value !! summary !! defining specification !! why dropped

|-
|[[rel-banner|banner]]||Was used to reference another document to be used as banner for this document (i.e. a form of "include" statement).|| HTML3 ||unknown

|-
| [[rel-begin|begin]] || identifies the author-defined start of a sequence of documents of which the current document is a node.
|| HTML4dropped||unknown

|-
| [[rel-biblioentry|biblioentry]] || identifies a bibliographic entry || HTML4dropped||unknown

|-
| [[rel-bibliography|bibliography]] || identifies a bibliography || HTML4dropped||unknown

|-
| [[rel-child|child]] (obsolete/superceded) || the target document is a hierarchical child, or subdocument, of the current document|| HTML4dropped||unknown

|-
| [[rel-citation|citation]] || the target is a bibliographic citation || HTML4dropped||unknown

|-
| [[rel-collection|collection]] || the target document is an collection that contains the current document || HTML4dropped||unknown

|-
| [[rel-definition|definition]] || identifies a definition of a term || HTML4dropped||unknown

|-
| [[rel-disclaimer|disclaimer]] || identifies a hypertext link to a legal disclaimer || HTML4dropped||unknown

|-
| [[rel-editor|editor]] || identifies a hypertext link to an editor || HTML4dropped||unknown

|-
| [[rel-end|end]] || identifies the author-defined end of a sequence of documents of which the current document is a node. || HTML4dropped||unknown

|-
| [[rel-footnote|footnote]] || the anchor is a footnote marker and the target is a footnote || HTML4dropped||unknown

|-
| [[rel-navigate|navigate]] || the target document contains information such as a image map that will help users to gain a sense of how and where to found information || HTML4dropped||unknown

|-
| [[rel-origin|origin]] || synonym for <code>top</code> || HTML4dropped||unknown

|-
| [[rel-parent|parent]] (obsolete/superceded) || the target document is the hierarchical parent, or container, of the current document|| HTML4dropped||unknown

|-
| [[rel-pointer|pointer]] || the target is a pointer to the real target. This value can be used by a user agent to perform a pre-fetch of the specified target for evaluation until the real target is reached || HTML4dropped||unknown

|-
| [[rel-publisher|publisher]] || identifies a hypertext link to a publisher || HTML4dropped||unknown

|-
| [[rel-sibling|sibling]] (obsolete/superceded) || the target document is a child of a common parent, or a hierarchical peer of the current document|| HTML4dropped||unknown

|-
| [[rel-top|top]] || the target document is the logical top node of the tree (see also <code>begin</code>) || HTML4dropped||unknown

|-
| [[rel-trademark|trademark]] || identifies a hypertext link to a trademark notice || HTML4dropped||unknown

|-
| [[rel-translation|translation]] || the target is a translation to another language || HTML4dropped||unknown

|-
| [[rel-urc|urc]] || identifies a Universal Resource Citation || HTML4dropped||unknown

|-
|}

== dropped without prejudice ==
In one known instance (from HTML4 to HTML5), some rel values were in an earlier version of a specification (or a proposal) and were dropped from a latter (draft) version, and it was noted that these values were dropped with the intent that they could still be proposed in a registry and thus they explicitly were not deprecated or obsoleted. This section documents such values as separate from the [[#dropped|dropped]] section.

In general, you {{should not}} use any dropped values.

If any such values have been superceded by standard values (see the first table on this page), then you {{must not}} use the dropped versions.

Rel values that were dropped without prejudice from a specification will be considered similar to new values that have never been specified.

If you know of additional rel values that were dropped without prejudice from an update to a specification, please cite a URL and quote from the group developing the specification that officially states from that group that the dropping of the values was done without prejudice, or equivalent statement (such as explicit allowance of external registration, proposal, and/or development).

This table serves a historical purpose. If you wish to propose a value from this table, please copy it and leave it in place.

Sources:
* Several rel values were [http://www.w3.org/Bugs/Public/show_bug.cgi?id=7475#c15 explicitly dropped from HTML5]. Per: [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Issue 118 Decision] ('''emphasis''' added): <blockquote>"The final proposal argues for the removal of some relation values, to wit, it suggests removal of '''index, up, first and last'''. It was pointed out in survey comments that these relations are already registered in the IANA link relation registry. Presumably, '''these relations could also be entered in whatever other registry or registries HTML5 adopts for this purpose'''...."Next Steps..."Since the relations to be removed are already registered at the IANA link relation registry, no further action is needed to include them there. WG members are '''free to register or record these relations elsehwere''' [sic], as well."</blockquote>

{| border="1"
|+
! rel value
! summary
! defining specification
! why dropped

|-
| [[rel-first|first]]
| synonym for <code>begin</code>
| HTML4dropped - never in an official spec
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-index|index]]
| Refers to a document providing an index for the current document.
| was in [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-last|last]]
| synonym for <code>end</code>
| HTML4dropped - never in an official spec
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-up|up]]
|When the document forms part of a hierarchy, this link references the immediate parent of the current document.
| was in [http://www.w3.org/MarkUp/html3/dochead.html HTML3] - but [http://www.w3.org/TR/html401/types.html#type-links dropped in HTML4]
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
|}

See related [http://dev.w3.org/html5/spec/links.html#linkTypes HTML5: Link types] for existing HTML5 specified rel values.

== rejected ==
Some rel values have been proposed and rejected. They are listed here to make that explicit. Authors {{must not}} use rejected rel values.

Source: [[rejected-formats]].

{| border="1"
|+
! rel value !! origin / proposal !! why rejected
|-
| [[rel-logo|logo]]
| [http://relogo.org Relogo.org]
| [[rejected-formats#Logo]]
|-
|[[rel-pavatar|pavatar]] || [http://pavatar.com/ pavatar] || [[rejected-formats#Pavatar]]
|-
|}

== tools ==
See [[implementations]].

== addtional external research ==
Here are some additional historical references to the development or rel-values which may be useful when researching values, especially why specific values may have been proposed but abandoned.
* 1996-06-07 [http://www.w3.org/MarkUp/draft-ietf-html-relrev-00.txt Hypertext links in HTML] (copies: [http://ftp.ics.uci.edu/pub/ietf/html/draft-ietf-html-relrev-00.txt ftp.ics.uci.edu])
* 1996-11-13 [http://www.w3.org/Architecture/NOTE-link Describing and Linking Web Resources]
* 1997-01-23 [http://lists.gnu.org/archive/html/lynx-dev/1997-01/msg00537.html LYNX-DEV Lynx and the LINK tag]
* 1997-01-24 [http://lists.w3.org/Archives/Public/w3c-sgml-wg/1997Jan/0357.html Taxonomy list]
* 1997-03-28 [http://www.w3.org/TR/WD-htmllink-970328 W3C Working Draft: Hypertext Links and Meta Information in HTML]

=== previous attempts at documenting ===
There have been previous attempts at documenting known rel values, most of which fell out of date due to being dependent on a single author maintaining them. They're listed here purely for historical reasons, and are not sufficient to be references of their own (since they're just individual curations of other references)
* [http://fantasai.tripod.com/qref/Appendix/LinkTypes/ltdef.html Link Type Definitions Glossary] by fantasai
* ...

== related ==
{{rel-related-pages}}
* [[elemental-microformats]]
* [[existing-rev-values]]
* [[existing-class-names]]

== copyright ==

{{cc-pd-license}}

existing-rel-values

2015-03-11T15:52:05Z

Andy sky: /* HTML5 link type extensions */ Dublin Core nonliteral-type resource references

<entry-title> existing rel values </entry-title>

This page contains tables of known HTML rel values from specifications, formats, proposals, brainstorms, and non-trivial [[POSH]] usage in the wild. In addition, dropped and rejected values are listed at the end for comprehensiveness.

usage: see [[rel-faq#How_is_rel_used|how is 'rel' used]]. Regarding rev, see: [[rel-faq#Should_rev_even_be_used|should 'rev' even be used]].

This page is also the official rel registry ([http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#other-link-types][http://www.w3.org/TR/html5/links.html#other-link-types]). Add new and proposed rel values to the following section:
* [[existing-rel-values#HTML5_link_type_extensions|HTML5 link type extension]]

== formats ==
These rel values are defined formats from specifications (HTML 4, microformats) are thus are recommended for general use. Alphabetically ordered by value.

Note:
* Do not add proposed rel values for HTML5 here, add them to the [[#HTML5_link_type_extensions|HTML5 link type extensions]] table.
* Do not add rel values you find in the wild to this table of rel formats, instead add them to the table in the [[existing-rel-values#POSH_usage|POSH section]].
* Do not add non-HTML rel values you find to this table of rel formats, instead add them to the table in the [[existing-rel-values#non_HTML_rel_values|non HTML rel values section]].
* Do not add rel values from obsolete/superceded proposals or drafts, instead add them to the table in the "dropped" section.

Sources:
* W3C Recommendations:
** [http://www.w3.org/TR/html401/types.html#h-6.12 HTML 4.01 section 6.12 Link types] (HTML4 Link types)
** [http://www.w3.org/TR/grddl/ Gleaning Resource Descriptions from Dialects of Languages] (GRDDL)
* [[microformats]] specifications
** [[xfn]]
** [[rel-license]]
** [[rel-nofollow]]

{| border="1"
|+
! Keyword
! Effect on <code>link</code>
! Effect on <code>a</code>, <code>area</code>
! Brief description (from the relevant specification where possible)
! Link to defining specification

|-
| [[rel-acquaintance|acquaintance]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be an acquaintance
| [[XFN]]

|-
| [[rel-alternate|alternate]]
| external resource
| external relation
| Designates substitute versions for the document in which the link occurs. When used together with the <code>lang</code> attribute, it implies a translated version of the document. When used together with the <code>media</code> attribute, it implies a version designed for a different medium (or media).
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-appendix|appendix]]
| allowed
| allowed
| Refers to a document serving as an appendix in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-bookmark|bookmark]]
| not allowed
| allowed
| Refers to a bookmark. A bookmark is a link to a key entry point within an extended document. The <code>title</code> attribute may be used, for example, to label the bookmark. Note that several bookmarks may be defined in each document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-chapter|chapter]]
| allowed
| allowed
| Refers to a document serving as a chapter in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-child|child]]
| not allowed
| external relation
| the referenced person is a child of the person represented by the current document
| [[XFN]]

|-
| [[rel-colleague|colleague]]
| not allowed
| external relation
| the referenced person is a colleague of the person represented by the current document
| [[XFN]]

|-
| [[rel-contact|contact]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be a contact
| [[XFN]]

|-
| [[rel-contents|contents]]
| allowed
| allowed
| Refers to a document serving as a table of contents. Some user agents also support the synonym ToC (from "Table of Contents").
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-copyright|copyright]]
| allowed
| allowed
| Refers to a copyright statement for the current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-co-resident|co-resident]]
| not allowed
| external relation
| the referenced person lives in the same residence as the person represented by the current document
| [[XFN]]

|-
| [[rel-co-worker|co-worker]]
| not allowed
| external relation
| the referenced person is a co-worker of the person represented by the current document
| [[XFN]]

|-
| [[rel-crush|crush]]
| not allowed
| external relation
| this person considers the referenced person to be a crush (i.e. has a crush on the referenced person)
| [[XFN]]

|-
| [[rel-date|date]]
| not allowed
| external relation
| this person considers the referenced person to be a date (i.e. is dating the referenced person)
| [[XFN]]

|-
| [[rel-friend|friend]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be a friend
| [[XFN]]

|-
| [[rel-glossary|glossary]]
| allowed
| allowed
| Refers to a document providing a list of terms and their definitions that pertain to the current document.||[http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-help|help]]
| allowed
| allowed
| Refers to a document offering help (more information, links to other sources information, etc.)
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-its-rules|its-rules]]
| allowed
| not allowed
| Refers to a document with external ITS rules.
| [http://www.w3.org/TR/its20/#selection-global-html5 Internationalization Tag Set (ITS) Version 2.0]

|-
| [[rel-kin|kin]]
| not allowed
| external relation
| the referenced person is part of the extended family of the person represented by the current document
| [[XFN]]

|-
| [[rel-license|license]]
| allowed
| allowed
| …indicates that the <nowiki>[referenced document]</nowiki> is a license for the current page.
| [[rel-license]]

|-
| [[rel-me|me]]
| external relation
| external relation
| the referenced document represents the same person as does the current document
| [[XFN]]

|-
| [[rel-met|met]]
| not allowed
| external relation
| this person has met the referenced person
| [[XFN]]

|-
| [[rel-muse|muse]]
| not allowed
| external relation
| the referenced person inspires the person represented by the current document
| [[XFN]]

|-
| [[rel-neighbor|neighbor]]
| not allowed
| external relation
| the referenced person lives nearby the person represented by the current document
| [[XFN]]

|-
| [[rel-next|next]]
| external relation
| external relation
| Refers to the next document in a linear sequence of documents. User agents may choose to preload the "next" document, to reduce the perceived load time.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-nofollow|nofollow]]
| not allowed
| external relation
| indicates that the destination of that hyperlink {{should-not}} be afforded any additional weight or ranking by user agents which perform link analysis upon web pages (e.g. search engines).
| [[rel-nofollow]]

|-
| [[rel-parent|parent]]
| not allowed
| external relation
| the referenced person is a parent of the person represented by the current document
| [[XFN]]

|-
| [[rel-prev|prev]]
| external relation
| external relation
| Refers to the previous document in an ordered series of documents. Some user agents also support the synonym "Previous".
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-previous|previous]]
| external relation
| external relation
| Synonym of <code>prev</code>
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-section|section]]
| allowed
| allowed
| Refers to a document serving as a section in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-sibling|sibling]]
| not allowed
| external relation
| the referenced person is a sibling of the person represented by the current document
| [[XFN]]

|-
| [[rel-spouse|spouse]]
| not allowed
| external relation
| the referenced person is a spouse of the person represented by the current document
| [[XFN]]

|-
| [[rel-start|start]]
| allowed
| allowed
| Refers to the first document in a collection of documents. This link type tells search engines which document is considered by the author to be the starting point of the collection.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-stylesheet|stylesheet]]
| external resource
| not allowed
| a style sheet for the current document used with the invisible <link href> element which is not ideal for content relationships. Content relationships should be user visible and thus uses with <a href> are strongly preferred. Unfortunately the use of stylesheet in user visible content like <a href> appears to be strictly theoretical.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-subsection|subsection]]
| allowed
| allowed
| Refers to a document serving as a subsection in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-sweetheart|sweetheart]]
| not allowed
| external relation
| this person considers the referenced person to be their sweetheart
| [[XFN]]

|-
| [[rel-tag|tag]]
| not allowed
| allowed
| …indicates that the <nowiki>[referenced document]</nowiki> is an author-designated "tag" (or keyword/subject) for the current page.
| [[rel-tag]]

|-
| [[rel-toc|toc]]
| allowed
| allowed
| Synonym of <code>contents</code> (from "Table Of Contents")
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-transformation|transformation]]
| allowed
| allowed
| Relates a source document to a transformation, usually represented in XSLT, that relates the source document syntax to the RDF graph syntax. Used in [[grddl|GRDDL]]
| [http://www.w3.org/TR/grddl/#transformation GRDDL]

|}

=== notes ===
*<code>rel="alternate"</code> can take further meaning from additional attributes, such as
** <code>rel="alternate" lang="fr"</code> (French language version of this page)
** <code>rel="alternate" media="print"</code> (printable version of this page)
** <code>rel="alternate" media="handheld"</code> (version of the page intended or better for handheld/portable devices like PDAs, cell phones, etc.)

*Synonyms such as "previous", "toc" are not as widely supported as the main term.

== proposals ==
A few rel values have been developed as drafts as a result of going through most of the microformats [[process]], and are thus listed here for your serious consideration. You may use these values, and if you find any problems with them please point them out on the respective "issues" page for the rel value.

{| border="1"
|+
! rel value !! summary !! proposed in !! external spec (if any)
|-
| [[rel-pronunciation|pronunciation]] || …indicates that the destination of the 'link' element is a document providing a pronunciation lexicon for speech-synthesis purposes. || [[rel-pronunciation]]
|-
| [[rel-directory|directory]] || …indicates that the destination of the hyperlink is a directory listing containing an entry for the current page. || [[rel-directory]]
|-
| [[rel-enclosure|enclosure]] || …indicates that the destination of that hyperlink is intended to be downloaded and cached. || [[rel-enclosure]] || [http://www.apps.ietf.org/rfc/rfc4287.html RFC4287]
|-
| [[rel-home|home]] || …indicates that the <nowiki>[referenced document]</nowiki> is the homepage of the site in which the current page appears. || [[rel-home]]
|-
| [[rel-payment|payment]] || …indicates that the destination of the hyperlink provides a way to show or give support (e.g. financial) for the current page|| [[rel-payment]]
|}

== HTML5 link type extensions ==

The following values are registered as link type extensions per the [http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#other-link-types requirements in the WHATWG HTML spec] and the [http://dev.w3.org/html5/spec/links.html#other-link-types requirements in the W3C HTML5 spec].

Before you register a new value:
* '''Please check the [[#formats|Formats table]] and DO NOT re-register''' rel values that are already there. Please note that the W3C HTML WG has made a [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Decision] to drop <code>index</code>, <code>up</code>, <code>first</code> and <code>last</code> from the HTML5 spec itself.
* '''Please check the [[#dropped|Dropped table]] and DO NOT register''' values that are already there. If you believe a rel value was dropped from another specification without prejudice, please provide link/cite to explicit text/decision stating as such, e.g. the value was merely postponed, or perhaps expected to be spun-out into its own spec from the group developing that specification.

Note that entries in the [[#formats|Formats table]] and entries that are already in HTML5 as built-in keywords are also considered extensions with the "Ratified" status.

Please make sure that registrations added here have all the required data filled in ''including'':
* "Effect on link"
* "Effect on a and area" and
* a link to a spec that documents the keyword ''as an HTML <code>rel</code> keyword''. (A spec that merely defines the file format of the link target but does not define the <code>rel</code> keyword for use in HTML is not the kind of spec that is being required here.)

Entries lacking any of the above required data will likely be removed.

Changes to this registry will not be reflected in validators in real time. But validators will typically get automatically updated with the changes within one week or so

{| border="1"
|+
! Keyword
! Effect on <code>link</code>
! Effect on <code>a</code>, <code>area</code>
! Brief description
! Link to specification
! Synonyms
! Status

|-
| [[rel-apple-touch-icon|apple-touch-icon]]
| External Resource
| Not allowed
| Specify a Webpage Icon for a “Web Clip”, or “touch icon”, for mobile devices (not limited to Apple devices).
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| probably redundant with rel=icon
| proposed

|-
| [[rel-apple-touch-icon-precomposed|apple-touch-icon-precomposed]]
| External Resource
| Not allowed
| Specify a Webpage Icon for a “Web Clip”, or “touch icon”, for mobile devices (not limited to Apple devices).
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| probably redundant with rel=icon
| proposed

|-
| [[rel-apple-touch-startup-image|apple-touch-startup-image]]
| External Resource
| Not allowed
| Specify a splashscreen for Web apps on iOS Safari
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| maybe redundant with rel=icon with the sizes attribute?
| proposed

|-
| [[rel-attachment|attachment]]
| Hyperlink
| Hyperlink
| The resource linked to is "attached" to this document, similar to email attachments. Used in WordPress.
| No formal specification
|
| proposed

|-
| [[WPVL_PRETTYPHOTO_REL]]
| Hyperlink
| Hyperlink
| Open lightbox with video
| No formal specification
|
| proposed

|-
| [[rel-authorization_endpoint|authorization_endpoint]]
| External Resource
| Not allowed
| Specify a hosted authorization server
| [http://indiewebcamp.com/distributed-indieauth distributed IndieAuth documentation]
|
| proposed

|-
| [[rel-canonical|canonical]]
| External Resource
| Not allowed
| Specifies the canonical URL for the current document in order to help avoid duplicate content.
| [http://en.wikipedia.org/wiki/Canonical_meta_tag Canonical meta tag] [http://www.Google.com/support/webmasters/bin/answer.py?answer=139066#2 Canonicalization at Google Webmaster Central] [http://www.Bing.com/community/site_blogs/b/webmaster/archive/2009/02/12/partnering-to-help-solve-duplicate-content-issues.aspx Microsoft Webmaster Center] [http://www.YSearchBlog.com/2009/02/12/fighting-duplication-adding-more-arrows-to-your-quiver/ Yahoo! Search Blog]
|
| proposed

|-
| [[rel-category|category]]
| Hyperlink
| Hyperlink
| Refers to a category assigned to the current document or post. Implemented by WordPress for indicating a relation between a blog post and a category.
| [[rel-category]]
|
| proposed

|-
| [[rel-component|component]]
| External Resource
| Not allowed
| Specify an HTML document that is treated as a component of this document.
| [https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/components/index.html Web Components]
|
| proposed

|-
| [[rel-chrome-webstore-item|chrome-webstore-item]]
| External Resource
| Not allowed
| Link tag to declare for app and extensions inline installations hosted in the Chrome Web Store.
| [https://developers.google.com/chrome/web-store/docs/inline_installation Using Inline Installation]
|
| proposed

|-
| [[rel_dcterms.(property)#conformsTo|DCTERMS.conformsTo]]
| External Resource
| Not allowed
| An established standard to which the described resource conforms.
<ref name=title group=dublincore>A ''plain (literal) value string'' may be associated to the resource as the value of the title attribute link element</ref>
<ref name=namespace group=dublincore>Requires Dublin Core namespace declaration: <code>'''<link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />'''</code></ref>
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.conformsTo" content="..." /></code>
| proposed

|-
| [[rel_dcterms.(property)#contributor|DCTERMS.contributor]]
| External Resource
| Not allowed
| An entity responsible for making contributions to the resource. Examples include a person, an organization, or a service.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.contributor" content="..." /></code>
| proposed

|-
| [[rel_dcterms.(property)#creator|DCTERMS.creator]]
| External Resource
| Not allowed
| An entity primarily responsible for making the resource. Examples include a person, an organization, or a service.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.creator" content="..." /></code>
| proposed

|-
| [[rel_dcterms.(property)#description|DCTERMS.description]]
| External Resource
| Not allowed
| An account of the resource. Description may include but is not limited to: an abstract, a table of contents, a graphical representation, or a free-text account of the resource.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.description" content="..." /></code>
| proposed

|-
| [[rel_dcterms.(property)#hasFormat|DCTERMS.hasFormat]]
| External Resource
| Not allowed
| A related resource that is substantially the same as the pre-existing described resource, but in another format.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel_dcterms.(property)#hasPart|DCTERMS.hasPart]]
| External Resource
| Not allowed
| A related resource that is included either physically or logically in the described resource.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel_dcterms.(property)#hasVersion|DCTERMS.hasVersion]]
| External Resource
| Not allowed
| A related resource that is a version, edition, or adaptation of the described resource.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel_dcterms.(property)#identifier|DCTERMS.identifier]]
| External Resource
| Not allowed
| An unambiguous reference to the resource within a given context.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.identifier" content="..." /></code>
| proposed

|-
| [[rel_dcterms.(property)#isFormatOf|DCTERMS.isFormatOf]]
| External Resource
| Not allowed
| A related resource that is substantially the same as the described resource, but in another format.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel_dcterms.(property)#isPartOf|DCTERMS.isPartOf]]
| External Resource
| Not allowed
| A related resource in which the described resource is physically or logically included.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel_dcterms.(property)#isReferencedBy|DCTERMS.isReferencedBy]]
| External Resource
| Not allowed
| A related resource that references, cites, or otherwise points to the described resource.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel_dcterms.(property)#isReplacedBy|DCTERMS.isReplacedBy]]
| External Resource
| Not allowed
| A related resource that supplants, displaces, or supersedes the described resource.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel_dcterms.(property)#isRequiredBy|DCTERMS.isRequiredBy]]
| External Resource
| Not allowed
| A related resource that requires the described resource to support its function, delivery, or coherence.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel_dcterms.(property)#isVersionOf|DCTERMS.isVersionOf]]
| External Resource
| Not allowed
| A related resource of which the described resource is a version, edition, or adaptation. Changes in version imply substantive changes in content rather than differences in format.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel_dcterms.(property)#license|DCTERMS.license]]
| External Resource
| Not allowed
| A legal document giving official permission to do something with the resource.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.license" content="..." /></code>
| proposed

|-
| [[rel_dcterms.(property)#mediator|DCTERMS.mediator]]
| External Resource
| Not allowed
| An entity that mediates access to the resource and for whom the resource is intended or useful. In an educational context, a mediator might be a parent, teacher, teaching assistant, or care-giver.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.mediator" content="..." /></code>
| proposed

|-
| [[rel_dcterms.(property)#publisher|DCTERMS.publisher]]
| External Resource
| Not allowed
| An entity responsible for making the resource available. Examples include a person, an organization, or a service.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.publisher" content="..." /></code>
| proposed

|-
| [[rel_dcterms.(property)#references|DCTERMS.references]]
| External Resource
| Not allowed
| A related resource that is referenced, cited, or otherwise pointed to by the described resource.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel_dcterms.(property)#relation|DCTERMS.relation]]
| External Resource
| Not allowed
| A related resource.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel_dcterms.(property)#replaces|DCTERMS.replaces]]
| External Resource
| Not allowed
| A related resource that is supplanted, displaced, or superseded by the described resource.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel_dcterms.(property)#requires|DCTERMS.requires]]
| External Resource
| Not allowed
| A related resource that is required by the described resource to support its function, delivery, or coherence.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel_dcterms.(property)#rightsHolder|DCTERMS.rightsHolder]]
| External Resource
| Not allowed
| A person or organization owning or managing rights over the resource.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
| It may be replaced by the literal value in form of <code><meta name="DCTERMS.rightsHolder" content="..." /></code>
| proposed

|-
| [[rel_dcterms.(property)#source|DCTERMS.source]]
| External Resource
| Not allowed
| A related resource from which the described resource is derived.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel_dcterms.(property)#subject|DCTERMS.subject]]
| External Resource
| Not allowed
| The topic of the resource.
<ref name=title group=dublincore />
<ref name=namespace group=dublincore />
| [http://dublincore.org/documents/dcmi-terms/ DCMI Metadata Terms]
|
| proposed

|-
| [[rel-disclosure|disclosure]]
| Not allowed
| External Resource
| The 'disclosure' Link Relation Type designates a list of patent disclosures or a particular patent disclosure itself made with respect to material for which such relation type is specified.
| [http://tools.ietf.org/html/draft-yevstifeyev-disclosure-relation The 'disclosure' Link Relation Type]
|
| proposed

|-
| [[rel-discussion|discussion]]
| Hyperlink
| Hyperlink
| Refers to discussion of the current document or post.
| [[rel-discussion]]
|
| proposed

|-
| [[rel-dns-prefetch|dns-prefetch]]
| External Resource
| Not allowed
| Tells the browser to perform dns lookup for host names ahead of use.
| [https://developer.mozilla.org/En/Controlling_DNS_prefetching Mozilla documentation] [http://dev.chromium.org/developers/design-documents/dns-prefetching Google documentation]
|
| proposed

|-
| [[rel-edit|edit]]
| Hyperlink
| Not allowed
| Tells the browser where the current page can be edited
| [http://universaleditbutton.org/Registered_MIME_type#Alternate_Linking_Scheme Universal Edit Button Alternate Linking Scheme]. Implemented in at least [http://mediawiki.org MediaWiki].
|
| proposed

|-
| [[rel-edituri|EditURI]]
| External Resource
| Not allowed
| A blogging auto discovery value, commonly used by WordPress
| [http://bitworking.org/projects/atom/draft-gregorio-09.html#Edit AtomAPI]
|
| proposed

|-
| [[rel-enclosure|enclosure]]
| External Resource
| External Resource
| Indicates that the referred resource is intended to be downloaded and cached.
| [[rel-enclosure]]
|
| proposed

|-
| [[rel-entry-content|entry-content]]
| Not allowed
| External Resource
| Indicates that the referenced document is an alternative display source for an Internet Explorer Web Slice.
| [http://msdn.microsoft.com/en-us/library/cc304073(VS.85).aspx#_alternative Web Slice format specification 0.9]
|
| proposed

|-
| [[rel-external|external]]
| Not allowed
| Hyperlink
| Indicates that the referenced document is not part of the same site as the current document.
| [[rel-external]]
|
| proposed

|-
| [[rel-home|home]]
| Hyperlink
| Hyperlink
| Refers to the top level document for the current document. It can be combined with 'alternate' to indicate a feed for the site of the current page.
| [[rel-home]]
|
| proposed

|-
| [[rel-hub|hub]]
| Hyperlink
| Hyperlink
| Refers to a hub that enables registration for notification of updates to the current page.
| [http://pubsubhubbub.googlecode.com/svn/trunk/pubsubhubbub-core-0.3.html#discovery PubSubHubbub Spec]
|
| proposed

|-
| [[rel-in-reply-to|in-reply-to]]
| Hyperlink
| Hyperlink
| Refers to an original post that the current page is a comment on or reply to.
| [[rel-in-reply-to]]
|
| proposed

|-
| [[rel-index|index]]
| Hyperlink
| Hyperlink
| Refers to a document providing a list of topics with pointers that pertain to the current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
|
| proposed

|-
| [[rel-indieauth|indieauth]]
| External Resource
| Not allowed
| the IndieAuth server for the relying party to contact for IndieAuth authentication
| [http://spec.indieauth.com/ IndieAuth specification]
|
| proposed

|-
| [[rel-issues|issues]]
| Hyperlink
| Hyperlink
| Refers to issues regarding the current document or specification.
| [[rel-discussion]]
|
| proposed

|-
| [[rel-lightbox|lightbox]]
| Not allowed
| Img Pop-Up
| Images with this attribute are displayed in a larger way than embedded in a website (or how you specified it) when clicked (e.g. with installed "Lightbox 2"-Plugin). When adding [group] to rel="lightbox" all images get a clickable button for next/prev; insert into <code><a rel="lightbox[group]"><img src="http:example.com/img.jpg"></a></code>
| [http://lokeshdhakar.com/projects/lightbox2/ Lightbox 2] (needs actual specification to be kept in this list, this link is just documentation of one implementation)
|
| proposed

|-
| [[rel-manifest|manifest]]
| External Resource
| Not allowed
| Imports or links to a manifest
| [http://w3c.github.io/manifest/#linking W3C Manifest for web application]
|
| proposed

|-
| [[rel-meta|meta]]
| External Resource
| Not allowed
| External metadata about the HTML document
| [http://www.w3.org/TR/2004/REC-rdf-syntax-grammar-20040210/#section-rdf-in-HTML W3C's RDF/XML Syntax Specification]
|
| proposed

|-
| [[rel-indieauth|micropub]]
| External Resource
| Not allowed
| the micropub endpoint for creating new posts
| [http://indiewebcamp.com/micropub Micropub scecification]
|
| proposed

|-
| [[rel-openid.delegate|openid.delegate]]
| External Resource
| Not allowed
| When the page that contains the link is used as an OpenID indentifier, the relying party perform sOpenID 1.1 authentication with the link target as the identifier instead.
| [http://openid.net/specs/openid-authentication-1_1.html#delegating_authentication OpenID Authentication 1.1]
|
| proposed

|-
| [[rel-openid.server|openid.server]]
| External Resource
| Not allowed
| The OpenID server for the relying party to contact for OpenID 1.1 authentication
| [http://openid.net/specs/openid-authentication-1_1.html#anchor4 OpenID Authentication 1.1]
|
| proposed

|-
| [[rel-openid2.local_id|openid2.local_id]]
| External Resource
| Not allowed
| When the page that contains the link is used as an OpenID indentifier, the relying party perform sOpenID 2.0 authentication with the link target as the identifier instead.
| [http://openid.net/specs/openid-authentication-2_0.html#rfc.section.7.3.3 OpenID Authentication 2.0]
|
| proposed

|-
| [[rel-openid2.provider|openid2.provider]]
| External Resource
| Not allowed
| The OpenID server for the relying party to contact for OpenID 2.0 authentication
| [http://openid.net/specs/openid-authentication-2_0.html#rfc.section.7.3.3 OpenID Authentication 2.0]
|
| proposed

|-
| [[rel-p3pv1|p3pv1]]
| External Resource
| Not allowed
| References a machine-readable privacy policy description in the P3P format
| [http://www.w3.org/TR/P3P/#syntax_link P3P spec]
|
| proposed

|-
| [[rel-pgpkey|pgpkey]]
| External Resource
| Not allowed
| Associates a PGP key with a Web page so that the Web page URL can be used as the commenter's URL in PGP-signed blog comments and the blogging system receiving the comment can fetch the key and verify the signature as belonging to the owner of the URL.
| [http://golem.ph.utexas.edu/~distler/blog/archives/000320.html PGP-Signed Comments]
|
| proposed

|-
| [[rel-pingback|pingback]]
| External Resource
| Not allowed
| gives the address of the pingback server that handles pingbacks to the current document
| [http://www.hixie.ch/specs/pingback/pingback Pingback]
|
| proposed

|-
| [[rel-prerender|prerender]]
| External Resource
| External Resource
| Prerenders the Web page targeted by the link including running it scripts.
| [[rel-prerender]]
|
| proposed

|-
| [[rel-profile|profile]]
| External Resource
| Contextual External Resource
| indicate[s] that the destination of that hyperlink is a metadata profile (e.g. an [[XMDP]] profile) for the current page or portion thereof. See also [[xmdp-brainstorming]].
| [http://microformats.org/wiki/rel-profile rel-profile]
|
| proposed

|-
| [[rel-publisher|publisher]]
| External Resource
| External Resource
| Indicates that the referenced document is a metadata profile (e.g., a social-media/real-name profile such as a Google+ profile) for the publisher of the current page, or some portion of the current page.
| [https://support.google.com/plus/answer/1713826?hl=en Google help page]
|
| proposed

|-
| [[rel-rendition|rendition]]
| External Resource
| External Resource
| Indicates some example rendering, interpretation, or depiction of the source. User agents may choose to execute, display, or render the target in-place; or navigate to the target.
| [http://www.globalmentor.com/specs/html-rel-rendition/ HTML rel rendition]
|
| proposed

|-
| [[rel-reply-to|reply-to]]
| External Resource
| Hyperlink
| indicates any mailbox(es) (i.e. email addresses) to which responses are to be sent. ''Note: this is distinct from the 'in-reply-to' value which refers to the originating document, not to the address where comments should be sent.
| [http://tools.ietf.org/html/rfc2822 RFC2822] (originally [http://tools.ietf.org/html/rfc822#section-4.4.3 RFC822])
|
| ratified

|-
| [[rel-service|service]]
| External Resource
| Not allowed
| Atom Publishing Protocol editing service autodiscovery.
| [http://wiki.whatwg.org/wiki/ServiceRelExtension Documentation on the WHATWG wiki]
|
| proposed

|-
| [[rel-shortlink|shortlink]]
| External Resource
| Not allowed
| Specifies the preferred shortened URL for the page.
| [http://code.google.com/p/shortlink/wiki/Specification shortlink spec]
|
| proposed

|-
| [[rel-sidebar|sidebar]]
| Hyperlink
| Hyperlink
| Indicates that the referenced document is intended to be shown in a secondary browsing context.
| [[rel-sidebar]]
|
| proposed

|-
| [[rel-sitemap|sitemap]]
| External Resource
| Not allowed
| Provides a link to an XML document describing the layout of the site.
| [[rel-sitemap]]
|
| proposed

|-
| [[rel-subresource|subresource]]
| External Resource
| Not allowed
| An external resource intended for use within the current page.
| [http://www.chromium.org/spdy/link-headers-and-server-hint/link-rel-subresource Chromium documentation]
|
| proposed

|-
| [[rel-syndication|syndication]]
| Hyperlink
| Hyperlink
| Refers to a page which is a syndicated copy of the current page.
| [[rel-syndication]]
|
| proposed

|-
| [[rel-timesheet|timesheet]]
| External Resource
| Not allowed
| Applies a timesheet to the document.
| [http://www.w3.org/TR/timesheets/#smilTimesheetsNS-Elements-Timesheet non-normative section in the Timesheet spec]
|
| proposed

|-
| [[rel-token_endpoint|token_endpoint]]
| External Resource
| Not allowed
| Specify an HTTP endpoint that micropub clients can use to obtain an access token given an authorization code
| [http://indiewebcamp.com/token-endpoint token endpoint documentation]
|
| proposed

|-
| [[rel-webmention|webmention]]
| External Resource
| Hyperlink
| gives the address of the webmention endpoint that handles webmentions to the current document
| [http://webmention.org/ WebMention specification]
|
| proposed

|-
| [[rel-widget|widget]]
| External Resource
| External Resource
| Autodiscovery for W3C widgets
| [http://dev.w3.org/2006/waf/widgets/Overview.html#linking-to-a-widget-package-from-a-html- non-normative section in the Widget packaging spec]
|
| proposed

|-
| [[rel-wlwmanifest|wlwmanifest]]
| External Resource
| Not allowed
| Windows Live Writer manifest autodiscovery
| [http://msdn.microsoft.com/en-us/library/bb463263.aspx documentation on MSDN]
|
| proposed

|-
| [[rel-image_src|image_src]]
| External Resource
| Not allowed
| Specify a Webpage Icon for use by Facebook, Yahoo, Digg, etc.
| Unknown, but see for instance [http://www.niallkennedy.com/blog/2009/03/enhanced-social-share.html this]
| probably redundant with rel=icon
| proposed

|-
| [[rel-cmis-acl|http://docs.oasis-open.org/ns/cmis/link/200908/acl]]
| External Resource
| External Resource
| Identifies the resource containing a CMIS ACL document for the link context
| [http://docs.oasis-open.org/cmis/CMIS/v1.0/cs01/cmis-spec-v1.0.html#_Toc243905525 CMIS 1.0, Section 3.4.3.4]
|
| proposed

|-
| [[rel-stylesheet/less|stylesheet/less]]
| External Resource
| Not allowed
| Less CSS framework stylesheets.
| [http://lesscss.org/#-client-side-usage Less CSS usage]
|
| proposed

|}

== brainstorming ==
Several rel values are being brainstormed as potential microformats and are thus listed here. If you find you have a use for such semantics in real world examples, consider trying out these values and provide feedback on the respective brainstorming page(s) with your results and experiences.

You may list new proposed rel values here, and even better if you can list and link to POSH uses in the wild.

{| border="1"
|+
! rel value !! summary !! brainstormed in and usage in the wild

|-
| [[rel-accessibility|accessibility]] || indicate[s] that the destination of that hyperlink contains accessibility information for the current page. || [http://www.brucelawson.co.uk/2009/rel-accessibility/ blog post] which itself uses the rel value in a <link> tag in the head of the document.

|-
| [[rel-author|author]] || indicate[s] that the destination of that hyperlink represents the author of the current page. Combines with [[rel-me|rel-me]] to chain authorship information. || Google has said it will index rel-Author in this [http://googlewebmastercentral.blogspot.com/2011/06/authorship-markup-and-web-search.html blog post], with further [http://www.google.com/support/webmasters/bin/answer.py?answer=1229920 discussion of the rel-me connection] See also [http://dev.w3.org/html5/spec/Overview.html#link-type-author the HTML5 spec]

|-
| [[rel-bibliography|bibliography]] || indicate[s] that the destination of that hyperlink is a bibliography for the current page. || [http://microformats.org/discuss/mail/microformats-discuss/2007-October/010863.html mailing list post, 2007-10-15]

|-
| [[rel-cite|cite]] || indicate[s] that the destination of that hyperlink is an authoritative source or a precedent to the current page. || [[distributed-conversation-brainstorming]]

|-
| [[rel-group|group]] || the referenced document represents a group to which the person represented by the current document belongs || [[group-brainstorming]]

|-
| [[rel-jslicense|jslicense]]
| Refers to a document with JavaScript source code and license information (also called a [http://www.gnu.org/licenses/javascript-labels.html JavaScript License Web Labels] page). We might want choose a keyword for this that is more general -- there are many situations besides JavaScript in which it is desirable or required by license agreements (e.g., GNU GPL) to make an offer of both the source code and a copy of a license when distributing object code versions of a given work.
|* Brainstorming page -- thoughts on the name?
* Ex. [http://www.eff.org EFF.org] (on <code>link</code>)
* Ex. [http://www.fsf.org FSF.org] (on <code>a</code>)
|-
| [[rel-longdesc|longdesc]] || Alternative to the img longdesc attribute, for use on visible links || [http://www.google.com/search?q=rel%3D%22longdesc%22 Google search for rel=longdesc in the wild] shows many sources of proposals. Please edit this to list the earliest and perhaps most recent/comprehensive proposal. No known real world POSH usage in the wild yet.

|-
| [[rel-map|map]] || Link to a map. Possibly embedded within an adr, hCard, geo or hCalendar. Parsers {{may}} attempt to parse the URL if it is a link to a known map site (e.g. Geohash, Google Maps, Multimap) and extract co-ordinates and other useful data. || (to [[User:TobyInk|TobyInk]] by email)

|-
| [[rel-member|member]] || the referenced document represents a member of the group represented by the current document || [[group-brainstorming]]

|-
| [[rel-m_PageScroll2id|m_PageScroll2id]] || JS to scroll to a defined ID || [[group-brainstorming]]

|-
| [[rel-preconnect|preconnect]] || indicates an origin that will be used to fetch required resources. Initiating an early connection, which includes the DNS lookup, TCP handshake, and optional TLS negotiation, allows the user agent to mask the high costs of connection establishment latency.|| [https://igrigorik.github.io/resource-hints/#preconnect resource hints draft]

|-
| [[rel-prefetch|prefetch]] || indicates the URL and content-type of a resource that is likely to be a required resource when the next action or navigation is triggered. Initiating an early fetch allows the user agent to mask the request latency of the resource and make it available sooner to the application.|| [https://igrigorik.github.io/resource-hints/#prefetch resource hints draft]

|-
| [[rel-preload|preload]] || indicates the URL and content-type of a resource that should be fetched as early as possible by the user agent. Initiating an early fetch allows the user agent to mask the request latency of the resource and make it available sooner to the application.|| [https://igrigorik.github.io/resource-hints/#preload resource hints draft]

|-
| [[rel-prerender|prerender]] || indicates the URL of the next navigation target. Initiating a prerender allows the user agent to deliver an instant navigation experience: the user agent downloads the top-level resource and its assets, and performs all of the processing steps required to show the page without actually showing it to the user.|| [https://igrigorik.github.io/resource-hints/#prerender resource hints draft]

|-
| [[rel-profile|profile]] || indicate[s] that the destination of that hyperlink is a metadata profile (e.g. an [[XMDP]] profile) for the current page or portion thereof || [[xmdp-brainstorming]]

|-
| [[rel-shortlink|shortlink]] || the referenced document represents the current document but with a shorter URL || [http://samj.net/2009/04/introducing-relshort-better-alternative.html blog post]
|-
| source || the referenced document represents the source code for the current document or project || [[source-brainstorming]] [http://adactio.com/journal/6667/ blog post]

|-
| vcalendar-parent || link from an event to a containing event || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]
|-
| vcalendar-child || link from an event to a contained event || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]
|-
| vcalendar-sibling || link from an event to a related event with the same container || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]

|-
| [[rel-status|status]] || the referenced document represents the status (or source of status updates) for the author of this document || [http://monkinetic.com/2009/11/24/status-autodiscovery-relstatus.html blog post]

|}

=== more brainstorming ===
See also:
* [[genealogy-brainstorming]] for some thoughts on possible additional values for family relationships (use existing [[XFN]] [[rel-parent|parent]], [[rel-child|child]], [[rel-sibling|sibling]], [[rel-spouse|spouse]], [[rel-kin|kin]] values first though)
* [[xpn-brainstorming]] for some thoughts on possible additional values for professional relationships (use existing [[XFN]] [[rel-co-worker|co-worker]], [[rel-colleague|colleague]] values first though)

== POSH usage ==
There are numerous rel values used as [[POSH]], both in the wild, whose origins are not necessarily known, nor are their meanings consistent. There are also numerous rel values from external proposals of varying degrees of merit. It is useful to document their existence and summarize their implied meanings/usage intent as research that may be used to perhaps take one or more of them thru the microformats [[process]] if there is both sufficient interest and sufficient in the wild usage.

Note: If a value is missing from this table, it may have either already been promoted by writing it up as a proposal, or demoted by being explicitly dropped. Please check the other tables first before adding to this table.

Note: this list is incomplete, please help complete it from the following sources:

External sources:
* [http://developer.mozilla.org/about/meta Meta Information in DevMo Docs] (DevMo)
* [http://wiki.mozilla.org/Microsummaries Microsummary]
* [http://lachy.id.au/dev/markup/specs/wclr/ Web Communication Link Relationships] (WCLR)
* [http://www.w3.org/MarkUp/Relationships.html W3C Link Relationship values draft] (LRdraft) - from a draft of the HTML spec circa 1991.
* [http://www.whatwg.org/specs/web-apps/current-work/multipage/section-links.html#linkTypes HTML5 draft] '''Liable to change'''
* [http://wiki.foaf-project.org/Autodiscovery FOAF Project Wiki: Autodiscovery] (FOAF)
* [http://www.apps.ietf.org/rfc/rfc4685.html RFC4685]
* [http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html Google Blog]

{| border="1"
|+
! rel value !! summary !! origin !! proposal(s)

|-
| [[rel-archive|archive]] || index of archived entries || unknown, perhaps Wordpress open source blogging software || WCLR

|-
| [[rel-archives|archives]] || Provides a link to a collection of records, documents, or other materials of historical interest. || || HTML5

|-
|[[rel-author|author]]||see brainstorming above for suggested use by google||unknown || DevMo / HTML5

|-
| [[rel-canonical|canonical]] || To help search engines disambiguate the same page with multiple representations || Google || [http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html Google]/[http://www.bing.com/community/blogs/webmaster/archive/2009/02/12/partnering-to-help-solve-duplicate-content-issues.aspx Microsoft]/[http://www.ysearchblog.com/2009/02/12/fighting-duplication-adding-more-arrows-to-your-quiver/ Yahoo!], [http://blog.ask.com/2009/02/ask-is-going-canonical.html Ask Jeeves]

|-
| [[rel-comment|comment]] || … || … || WCLR

|-
| [[rel-contribution|contribution]] || … || … || WCLR

|-
| [[rel-edituri|EditURI]]
| Location of the xml-rpc gateway for a Wordpress install that allows external programs to add, edit and delete posts. Used by "[http://codex.wordpress.org/Weblog_Client WordPress blog client]" software for automating posting and updating blog content from your desktop. || Seen in [http://www.wordpress.org/ WordPress], e.g. [http://www.tom-watson.co.uk/]. || Description stubbed in [[rel-edituri]].

|-
| [[rel-endorsed|endorsed]] || … || … || WCLR

|-
| [[rel-fan|fan]] || xxxx. || … || [[hcard-user-profile-authoring]]

|-
| [[rel-feed|feed]] || Gives the address of a syndication feed for the current document. || … || WCLR/ HTML5

|-
| [[rel-footnote|footnote]] || Location of the footnote on a link to a footnote. || Markdown preprocessors such as [http://maruku.rubyforge.org/ Maruku] || HTML5

|-
| [[rel-icon|icon]] || Imports an icon to represent the current document. (Allowed in <code>link</code> only) || [http://dev.w3.org/html5/spec-LC/links.html#rel-icon HTML5] || WCLR/HTML5

|-
| [[rel-kinetic-stylesheet|kinetic-stylesheet]] || Imports a [http://kssproject.org/ KSS] 'kinetic stylesheet' to bind dynamic behavior to elements || Used in the [http://plone.org Plone] Content Management System || …

|-
| [[rel-lightbox|lightbox]] || Hook - Indicates that following the link will trigger a "lightbox" script (Allowed in <code>link</code> only) || ([http://www.google.co.uk/search?q=rel%3D%22lightbox%22 Google search for rel=lightbox in the wild]) || …

|-
| [[rel-lightbox|lightbox[group_name]]] || Used by lightbox scripts to group different sets of images together. Images from one group will not appear in another group's lightbox. See also "lightbox". || [http://lokeshdhakar.com/projects/lightbox2/#how Lightbox 2] || …

|-
| [[rel-prettyPhoto|prettyPhoto]] || See also "lightbox" || ([http://www.google.fr/search?q=rel%3D%22prettyphoto%22 Google search for rel="prettyphoto" in the wild]) || …

|-
| [[rel-clearbox|clearbox]] || See also "lightbox" || ([http://www.google.fr/search?q=rel%3D%22clearbox%22 Google search for rel="clearbox" in the wild]) || …

|-
| [[rel-made|made]] || … || … || LRdraft

|-
| [[rel-meta|meta]] || … || [http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/#transport 1999 W3C RDF syntax REC] || FOAF

|-
| [[rel-microsummary|microsummary]]|| … || … ||[http://wiki.mozilla.org/Microsummaries Microsummary], be aware of: [[page-summary-formats#Issues_2|microsummary issues]]

|-
| [[rel-noreferrer|noreferrer]] || indicates that no referrer information is to be leaked when following the link. || [http://dev.w3.org/html5/spec-LC/links.html#rel-noreferrer HTML5] || HTML5

|-
| [[rel-openid-delegate|openid.delegate]] || … || ([http://www.google.co.uk/search?q=%22rel%3Dopenid%22 Google search for rel=openid.* in the wild]) || …

|-
| [[rel-openid-server|openid.server]] || … || ([http://www.google.co.uk/search?q=%22rel%3Dopenid%22 Google search for rel=openid.* in the wild]) || …

|-
| [[rel-permalink|permalink]] || … || … || WCLR

|-
| [[rel-pgpkey|pgpkey]] || (see also rel-publickey) || … || [http://golem.ph.utexas.edu/~distler/blog/archives/000320.html], [http://golem.ph.utexas.edu/~distler/blog/archives/000325.html]

|-
| [[rel-pingback|pingback]] || Gives the address of the pingback server that handles pingbacks to the current document. (Allowed in <code>link</code> only) || … || WCLR/ HTML5

|-
| [[rel-popover|popover]] || Used by a JS widget to display a large, descriptive tooltip. || [http://twitter.github.com/bootstrap Twitter's Bootstrap] [http://twitter.github.com/bootstrap/javascript.html#popovers Popover.js] || …

|-
| [[rel-prefetch|prefetch]] || Specifies that the target resource should be pre-emptively cached. (Allowed in <code>link</code> only) || … || HTML5

|-
| [[rel-privacy|privacy]] || Specifies that the target resource is the privacy policy. || … || …

|-
| [[rel-publickey|publickey]] || (see also rel-pgpkey) || … || [http://rasterweb.net/raster/2002/12/12/20021212072812/]

|-
| [[rel-referral|referral]] || … || … || WCLR

|-
| [[rel-related|related]] || … || … || WCLR

|-
| [[rel-replies|replies]] || indicates a continued thread || unknown || [http://www.apps.ietf.org/rfc/rfc4685.html RFC4685]

|-
| [[rel-resource|resource]] || … || … || WCLR

|-
| [[rel-search|search]] || … || unknown || unknown

|-
| [[rel-sitemap|sitemap]] || Links to a site map document. || … || http://www.sitemaps.org/

|-
| [[rel-sponsor|sponsor]] || … || … || WCLR

|-
| [[rel-tooltip|tooltip]] || Used by a JS widget to display a tooltip similar (though more customizable) to what is shown by browsers if the 'title' attribute is present. || [http://twitter.github.com/bootstrap Twitter's Bootstrap] [http://twitter.github.com/bootstrap/javascript.html#tooltips Tooltip.js] (and likely other JS tools) || …

|-
| [[rel-trackback|trackback]] || … || unknown, perhaps open source Movable Type blogging software || WCLR

|-
| [[rel-unendorsed|unendorsed]] || (probably redundant to [[rel-nofollow|nofollow]]) || … || WCLR

|-
| [[rel-user|user]] || … || … || WCLR
|-
| [[rel-wlwmanifest|wlwmanifest]] || Used by "[http://explore.live.com/windows-live-writer Windows Live Writer]," a Microsoft [http://codex.wordpress.org/Weblog_Client blog client] for automating posting and updating blog content from your desktop. || Seen in [http://www.wordpress.org/ WordPress], e.g. [http://www.tom-watson.co.uk/]. Similar values are probably used by other blog content management systems as well. || …

|}

=== WCLR ===

The WCLR proposal is described by its author (in e-mail, 2007-09-25) as:

<blockquote>
…now effectively obsolete, since HTML5 and Microformats cover all the worthwhile relationships in that already.

These are [http://www.whatwg.org/specs/web-apps/current-work/multipage/section-links.html#linkTypes covered by HTML5 already]:

* permalink -> bookmark
* archive -> archives
* feed
* pingback
* unendorsed -> nofollow

The rest now seem unnecessary.
</blockquote>

Nonetheless, there may be some mileage in using them in microformats, at least until HTML5 is widely available.

== Dublin Core ==
In the past, Dublin Core values have been added to this page in the table about HTML5 features, but no examples, nor an actual specification explicitly stating how the value(s) should be used in HTML could be found. The linked specifications below have been updated so we should start considering Dublin Core values accordingly.

{| border="1"
|+
! rel value !! summary !! source
|-
| schema.DC || a specification of all metadata terms maintained by the Dublin Core Metadata Initiative, with regard to the fifteen terms of the Dublin Core Metadata Element Set already published || [http://www.dublincore.org/documents/dcq-html/ Dublin Core]

|-
| schema.DCTERMS || a specification of all metadata terms maintained by the Dublin Core Metadata Initiative, reflecting the changes described more fully in the 2012 document "Maintenance changes to DCMI Metadata Terms" [http://dublincore.org/usage/decisions/2012/dcterms-changes/] || [http://www.dublincore.org/documents/dcq-html/ Dublin Core]
|-
|}

'''Issues need updating given new information from linked resources.'''

Notes:
* Dublin Core. This search may help: [http://www.google.co.uk/search?as_q=rel%3Dschema.*&hl=en&num=10&btnG=Google+Search&as_epq=&as_oq=&as_eq=&lr=&as_ft=i&as_filetype=&as_qdr=all&as_occt=any&as_dt=i&as_sitesearch=http%3A%2F%2Fdublincore.org&as_rights=&safe=images].
** '''examples from that search only use invisible <code><link href></code> element'''. At first glance it appears the results from the search show only uses with the invisible <code><link href></code> element which is not ideal for content relationships. Content relationships should be user visible and thus uses with <code><a href></code> are strongly preferred.
*** [http://www.ietf.org/rfc/rfc2731.txt RFC2731] defines <code>rel="schema.AC"</code> and <code>rel="schema.RC"</code> with the pattern <code>rel="schema.PREFIX"</code> as a syntax for defining namespaces for use in meta[@name], *[@rel], *[@rev] and (as per eRDF) *[@class] attributes. A link to a Dublin Core metadata schema is generally not suitable for end users, so <code><link href></code> appears to be more appropriate than <code><a href></code> for those that use Dublin Core metadata schemas.
*** The scheme proposed above provides metadata namespace declarations. As described by DCMI specifications, such indications '''cannot''' be provided w/o a suitable namespace. In order to give complete pieces of information, the correct description set must be: <code><link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"></code> (for the namespace declaration, followed by) <code><meta name="DCTERMS.<nowiki>[element]</nowiki>" content="<nowiki>[element.value]</nowiki>"></code> for related elements.
**** Note: [http://purl.org/dc/terms/ schema.DCTERMS] is conventionally related to an upgraded elements list than [http://purl.org/dc/elements/1.1/ schema.DC] and should be preferred as rel values. Both are discussed here for subject completeness)
** '''proposal to use in content currently only theoretical'''. Thus unfortunately the use of Dublin Core in user visible content like <code><a href></code> appears to be strictly theoretical. See [http://microformats.org/discuss/mail/microformats-discuss/2008-January/011445.html microformats-discuss/2008-January/011445.html] for a proposal to use Dublin Core in user visible content.
*** '''recent improvements'''. DCMI solves some trouble concerning metadata through the ''description set model''. Some of these informations cannot currently be provided in any standard ways other than DC, namely dates, validity and periodicity. Following this public bug report ([https://www.w3.org/Bugs/Public/show_bug.cgi?format=multiple&id=22520]), the correct namespace declaration for DC and DCTERMS metadata are now considered valid HTML code. We '''must''' encourage this practice both for internal usefulness and for shared practices.

* The Dublin Core document [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] is a specification for, and gives examples of, both <link rel="schema.DC" href="http://purl.org/dc/elements/1.1/"> and <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/">. Note that Dublin Core encourages the use of DCTERMS elements over DC. A list of projects which use Dublin Core metadata is maintained [http://dublincore.org/projects/ here].
* [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] also includes examples of <link rel="DCTERMS.[element]" href="">, where [element] = subject, isReferencedBy, creator, and publisher. The <link> tag is used instead of the <meta> tag whenever the content is a URL. (Note that this use is different from, but related to, <link rel="schema.DCTERMS" href="">.) Potentially, ''any'' of the 55 DCTERMS elements could be used in this way, and this could include use in HTML 5.
** As said before, HTML5 validators now allow the use of <code><link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"></code> for namespace declarations.

== Use with HTTP Link Header ==
You can also use any of the rel values (that are allowed for link elements) with HTTP Link Headers,

Example: returning a Javascript file with a license (since JS itself has no way to indicate a license)
<source lang=text>
Link: <http://creativecommons.org/publicdomain/zero/1.0/>; rel="license"
</source>

For multiple licenses (e.g. CC-SA and GPL), simply use multiple <code>Link:</code> headers.
<source lang=text>
Link: <http://creativecommons.org/licenses/by-sa/3.0/>; rel="license"
Link: <http://www.gnu.org/licenses/gpl.html>; rel="license"
</source>

Example: similarly, linking to a copyright statement for an image:
<source lang=text>
Link: <http://example.org/copyright.html>; rel="copyright"
</source>
or providing a brief inline copyright statement:
<source lang=text>
Link: <data:text/plain;charset=utf-8,Copyright 2013 ExampleCo, All Rights Reserved.>; rel="copyright"
</source>

== unspecified ==
Some rel values have been added to this page perhaps in one of the tables above, but no examples, nor an actual specification explicitly stating that the value(s) should be used in the HTML 'rel' attribute could be found. They are listed here in the hopes someone can discover more specific/precise URLs to examples or specifications about them (preferably both). Until such precise URLs to examples/specs are provided, the values can be treated as they are purely theoretical and thus of little interest.

A simple list here is sufficient.

== non HTML rel values ==
There are markup languages other than HTML that also have a rel attribute, often based upon the HTML rel attribute.
It is useful to document some of these other languages and their rel values for both reference purposes, and to provide background research for the possible development and re-use of these values in HTML, as [[poshformats]] or [[microformats]]

Sources:
* [[Atom]] [[RFC4287]] specification.
* See http://www.iana.org/assignments/link-relations.html for more.
* See [http://amundsen.com/media-types/maze/format/#link-relations Maze+XML]
* See [http://amundsen.com/media-types/collection/format/#link-relations Collection+JSON]
* See [http://www.opensearch.org/Specifications/OpenSearch/1.1#Url_rel_values OpenSearch]
* See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

{| border="1"
|+
! rel value !! summary (from the relevant specification where possible)) !! defining specification

|-
| self
| From http://www.ietf.org/rfc/rfc4287.txt : <blockquote>The value "self" signifies that the IRI in the value of the href attribute identifies a resource equivalent to the containing element.</blockquote>
| [[Atom]] http://www.ietf.org/rfc/rfc4287.txt

|-
| http://gdata.youtube.com/schemas/2007#in-reply-to || See http://code.google.com/apis/youtube/2.0/developers_guide_protocol_comments.html || YouTube extension to Atom

|-
| collection || Refers to a resource which represents a collection of which the current resource is a member.

When used in the Maze+XML media type, the associated URI returns the available collection of mazes.
|| Maze+XML, Collection+JSON, OpenSearch

|-
| east || Refers to a resource to the "east" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the east in the active maze.

|| Maze+XML

|-
| exit || Refers to a resource that represents the exit or end of the current client actvity or process.

When used in the Maze+XML media type, the associated URI points to the final exit resource of the active maze.

|| Maze+XML

|-
| north || Refers to a resource that is "north" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the north in the active maze.

|| Maze+XML

|-
| south || Refers to a resource that is "south" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the south in the active maze.

|| Maze+XML

|-
| [[rel-via|via]] || Identifies a resource that is the source of the information in the context. || Atom 1.0 Syndication format (RFC 4287)

|-
| west || Refers to a resource that is "west" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the west in the active maze.

|| Maze+XML

|-
| item || The target IRI points to a resource that is a member of a collection represented by the context IRI. || Collection+JSON

|-
| create-form || When included in a resource, the "create-form" link relation MAY identify a target resource that represents the form to append a new member to the link context. || See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

|-
| edit-form || When included in a resource, the "edit-form" link relation identifies a target resource that represents the form for editing associated resource. || See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

|-
| lightframe || Opens the target in a lightbox. On inclusion it provides a simple target the lightframe and loads the content in a lightbox effect || Lightbox

|-
| superbox[image] || jQuery Superbox! is a script which allows you display windows with the lightbox effect. || superbox

|-
| wp-video-lightbox || wp-video-lightbox! is a rel to anchor tag script display videos with the lightbox effect. || wp-video-lightbox

|-
| youtube || Opens the target youtube video in using the Swipebox Plugin || Swipebox

|-
| shadowbox || shadowbox is a jQuery script for images displaying with the "lightbox" effects. || shadowbox

|-
| permission || When included in a resource, the "permission" link relation MAY identify a target resource that represents the list of entities that can access or modify the resource in the link context. || See [http://cdoc.io/spec.html#permission-link-relation Collection Document Media Type Specification]

|-
| version-history
| When included on a versioned resource, this link points to a resource containing the version history for this resource.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| latest-version
| When included on a versioned resource, this link points to a resource containing the latest (e.g., current) version.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| working-copy
| When included on a versioned resource, this link points to a working copy for this resource.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| working-copy-of
| When included on a working copy, this link points to the versioned resource from which this working copy was obtained.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| predecessor-version
| When included on a versioned resource, this link points to a resource containing the predecessor version in the version history.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| successor-version
| When included on a versioned resource, this link points to a resource containing the successor version in the version history.
| [http://tools.ietf.org/html/rfc5829 RFC 5829]

|-
| ... || ... || ...

|}

== dropped ==
The following rel values were in earlier version(s) of specification(s) and it is presumed by their absence from the most recent version of the respective specification(s) that they have been deprecated or obsoleted.

In general, you {{should not}} use any dropped values.

If any such values have been superceded by standard values (see the first table on this page), then you {{must not}} use the dropped versions.

In particular:
* if a rel value was in a draft and is missing (without explanation) from the final spec, or
* if a rel value was in a previous version of and is missing (without explanation) from an update to the specification (even a draft update)

Then absent any other information or explanation, it is presumed that the group/editors working on that specification decided to explicitly drop it (either in development, or in the updated version) and thus it should be obsoleted (not re-registered).

If you wish to add them, please research why such values were omitted from latter specifications before doing so. If you do discover the reasoning, please add a short statement or link to thereof into the appropriate place in the following table.

If there is more data, e.g. a link to an email of discussion of the spec development that explains ''why'' the rel value was dropped, and it explicitly states, e.g. it was without prejudice, or merely post-poned, or perhaps expected to be spun-out into its spec (or some other explicit positive reason), then it makes to link/cite that explicit text as part of a proposal.

Sources:
* [http://www.w3.org/MarkUp/html3/ HTML3] (HTML3) / has been superceded by [http://www.w3.org/MarkUp/Wilbur/ HTML 3.2] - which itself has been superceded by [http://www.w3.org/TR/REC-html40 HTML 4.0] - which itself has been updated by [http://w3.org/TR/html401 HTML 4.01], commonly referred to as "HTML 4" in this wiki and other places.)
* [http://www.w3.org/TR/relations.html Proposed HTML 4.0 link types] (HTML4dropped) - obsoleted/superceded by the HTML 4.0 Recommendation. Any values that were in the "Proposed HTML 4.0 link types" document but didn't make it into the HTML 4.0 Recommendation were thus explicitly dropped and should be avoided.

{| border="1"
|+
! rel value !! summary !! defining specification !! why dropped

|-
|[[rel-banner|banner]]||Was used to reference another document to be used as banner for this document (i.e. a form of "include" statement).|| HTML3 ||unknown

|-
| [[rel-begin|begin]] || identifies the author-defined start of a sequence of documents of which the current document is a node.
|| HTML4dropped||unknown

|-
| [[rel-biblioentry|biblioentry]] || identifies a bibliographic entry || HTML4dropped||unknown

|-
| [[rel-bibliography|bibliography]] || identifies a bibliography || HTML4dropped||unknown

|-
| [[rel-child|child]] (obsolete/superceded) || the target document is a hierarchical child, or subdocument, of the current document|| HTML4dropped||unknown

|-
| [[rel-citation|citation]] || the target is a bibliographic citation || HTML4dropped||unknown

|-
| [[rel-collection|collection]] || the target document is an collection that contains the current document || HTML4dropped||unknown

|-
| [[rel-definition|definition]] || identifies a definition of a term || HTML4dropped||unknown

|-
| [[rel-disclaimer|disclaimer]] || identifies a hypertext link to a legal disclaimer || HTML4dropped||unknown

|-
| [[rel-editor|editor]] || identifies a hypertext link to an editor || HTML4dropped||unknown

|-
| [[rel-end|end]] || identifies the author-defined end of a sequence of documents of which the current document is a node. || HTML4dropped||unknown

|-
| [[rel-footnote|footnote]] || the anchor is a footnote marker and the target is a footnote || HTML4dropped||unknown

|-
| [[rel-navigate|navigate]] || the target document contains information such as a image map that will help users to gain a sense of how and where to found information || HTML4dropped||unknown

|-
| [[rel-origin|origin]] || synonym for <code>top</code> || HTML4dropped||unknown

|-
| [[rel-parent|parent]] (obsolete/superceded) || the target document is the hierarchical parent, or container, of the current document|| HTML4dropped||unknown

|-
| [[rel-pointer|pointer]] || the target is a pointer to the real target. This value can be used by a user agent to perform a pre-fetch of the specified target for evaluation until the real target is reached || HTML4dropped||unknown

|-
| [[rel-publisher|publisher]] || identifies a hypertext link to a publisher || HTML4dropped||unknown

|-
| [[rel-sibling|sibling]] (obsolete/superceded) || the target document is a child of a common parent, or a hierarchical peer of the current document|| HTML4dropped||unknown

|-
| [[rel-top|top]] || the target document is the logical top node of the tree (see also <code>begin</code>) || HTML4dropped||unknown

|-
| [[rel-trademark|trademark]] || identifies a hypertext link to a trademark notice || HTML4dropped||unknown

|-
| [[rel-translation|translation]] || the target is a translation to another language || HTML4dropped||unknown

|-
| [[rel-urc|urc]] || identifies a Universal Resource Citation || HTML4dropped||unknown

|-
|}

== dropped without prejudice ==
In one known instance (from HTML4 to HTML5), some rel values were in an earlier version of a specification (or a proposal) and were dropped from a latter (draft) version, and it was noted that these values were dropped with the intent that they could still be proposed in a registry and thus they explicitly were not deprecated or obsoleted. This section documents such values as separate from the [[#dropped|dropped]] section.

In general, you {{should not}} use any dropped values.

If any such values have been superceded by standard values (see the first table on this page), then you {{must not}} use the dropped versions.

Rel values that were dropped without prejudice from a specification will be considered similar to new values that have never been specified.

If you know of additional rel values that were dropped without prejudice from an update to a specification, please cite a URL and quote from the group developing the specification that officially states from that group that the dropping of the values was done without prejudice, or equivalent statement (such as explicit allowance of external registration, proposal, and/or development).

This table serves a historical purpose. If you wish to propose a value from this table, please copy it and leave it in place.

Sources:
* Several rel values were [http://www.w3.org/Bugs/Public/show_bug.cgi?id=7475#c15 explicitly dropped from HTML5]. Per: [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Issue 118 Decision] ('''emphasis''' added): <blockquote>"The final proposal argues for the removal of some relation values, to wit, it suggests removal of '''index, up, first and last'''. It was pointed out in survey comments that these relations are already registered in the IANA link relation registry. Presumably, '''these relations could also be entered in whatever other registry or registries HTML5 adopts for this purpose'''...."Next Steps..."Since the relations to be removed are already registered at the IANA link relation registry, no further action is needed to include them there. WG members are '''free to register or record these relations elsehwere''' [sic], as well."</blockquote>

{| border="1"
|+
! rel value
! summary
! defining specification
! why dropped

|-
| [[rel-first|first]]
| synonym for <code>begin</code>
| HTML4dropped - never in an official spec
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-index|index]]
| Refers to a document providing an index for the current document.
| was in [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-last|last]]
| synonym for <code>end</code>
| HTML4dropped - never in an official spec
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-up|up]]
|When the document forms part of a hierarchy, this link references the immediate parent of the current document.
| was in [http://www.w3.org/MarkUp/html3/dochead.html HTML3] - but [http://www.w3.org/TR/html401/types.html#type-links dropped in HTML4]
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
|}

See related [http://dev.w3.org/html5/spec/links.html#linkTypes HTML5: Link types] for existing HTML5 specified rel values.

== rejected ==
Some rel values have been proposed and rejected. They are listed here to make that explicit. Authors {{must not}} use rejected rel values.

Source: [[rejected-formats]].

{| border="1"
|+
! rel value !! origin / proposal !! why rejected
|-
| [[rel-logo|logo]]
| [http://relogo.org Relogo.org]
| [[rejected-formats#Logo]]
|-
|[[rel-pavatar|pavatar]] || [http://pavatar.com/ pavatar] || [[rejected-formats#Pavatar]]
|-
|}

== tools ==
See [[implementations]].

== addtional external research ==
Here are some additional historical references to the development or rel-values which may be useful when researching values, especially why specific values may have been proposed but abandoned.
* 1996-06-07 [http://www.w3.org/MarkUp/draft-ietf-html-relrev-00.txt Hypertext links in HTML] (copies: [http://ftp.ics.uci.edu/pub/ietf/html/draft-ietf-html-relrev-00.txt ftp.ics.uci.edu])
* 1996-11-13 [http://www.w3.org/Architecture/NOTE-link Describing and Linking Web Resources]
* 1997-01-23 [http://lists.gnu.org/archive/html/lynx-dev/1997-01/msg00537.html LYNX-DEV Lynx and the LINK tag]
* 1997-01-24 [http://lists.w3.org/Archives/Public/w3c-sgml-wg/1997Jan/0357.html Taxonomy list]
* 1997-03-28 [http://www.w3.org/TR/WD-htmllink-970328 W3C Working Draft: Hypertext Links and Meta Information in HTML]

=== previous attempts at documenting ===
There have been previous attempts at documenting known rel values, most of which fell out of date due to being dependent on a single author maintaining them. They're listed here purely for historical reasons, and are not sufficient to be references of their own (since they're just individual curations of other references)
* [http://fantasai.tripod.com/qref/Appendix/LinkTypes/ltdef.html Link Type Definitions Glossary] by fantasai
* ...

== related ==
{{rel-related-pages}}
* [[elemental-microformats]]
* [[existing-rev-values]]
* [[existing-class-names]]

== copyright ==

{{cc-pd-license}}

existing-rel-values

2013-07-02T00:59:44Z

Andy sky: Updated information table and notes about Dublin Core metadata namespaces. Table moved nex to HTML5 proposals.

<entry-title> existing rel values </entry-title>

This page contains tables of known HTML rel values from specifications, formats, proposals, brainstorms, and non-trivial [[POSH]] usage in the wild. In addition, dropped and rejected values are listed at the end for comprehensiveness.

usage: see [[rel-faq#How_is_rel_used|how is 'rel' used]]. Regarding rev, see: [[rel-faq#Should_rev_even_be_used|should 'rev' even be used]].

== formats ==
These rel values are defined formats from specifications (HTML 4, microformats) are thus are recommended for general use. Alphabetically ordered by value.

Note:
* Do not add proposed rel values for HTML5 here, add them to the [[#HTML5_link_type_extensions|HTML5 link type extensions]] table.
* Do not add rel values you find in the wild to this table of rel formats, instead add them to the table in the [[existing-rel-values#POSH_usage|POSH section]].
* Do not add non-HTML rel values you find to this table of rel formats, instead add them to the table in the [[existing-rel-values#non_HTML_rel_values|non HTML rel values section]].
* Do not add rel values from obsolete/superceded proposals or drafts, instead add them to the table in the "dropped" section.

Sources:
* W3C Recommendations:
** [http://www.w3.org/TR/html401/types.html#h-6.12 HTML 4.01 section 6.12 Link types] (HTML4 Link types)
** [http://www.w3.org/TR/grddl/ Gleaning Resource Descriptions from Dialects of Languages] (GRDDL)
* [[microformats]] specifications
** [[xfn]]
** [[rel-license]]
** [[rel-nofollow]]

{| border="1"
|+
! Keyword
! Effect on <code>link</code>
! Effect on <code>a</code>, <code>area</code>
! Brief description (from the relevant specification where possible)
! Link to defining specification

|-
| [[rel-acquaintance|acquaintance]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be an acquaintance
| [[XFN]]

|-
| [[rel-alternate|alternate]]
| external resource
| external relation
| Designates substitute versions for the document in which the link occurs. When used together with the <code>lang</code> attribute, it implies a translated version of the document. When used together with the <code>media</code> attribute, it implies a version designed for a different medium (or media).
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-appendix|appendix]]
| allowed
| allowed
| Refers to a document serving as an appendix in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-bookmark|bookmark]]
| not allowed
| allowed
| Refers to a bookmark. A bookmark is a link to a key entry point within an extended document. The <code>title</code> attribute may be used, for example, to label the bookmark. Note that several bookmarks may be defined in each document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-chapter|chapter]]
| allowed
| allowed
| Refers to a document serving as a chapter in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-child|child]]
| not allowed
| external relation
| the referenced person is a child of the person represented by the current document
| [[XFN]]

|-
| [[rel-colleague|colleague]]
| not allowed
| external relation
| the referenced person is a colleague of the person represented by the current document
| [[XFN]]

|-
| [[rel-contact|contact]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be a contact
| [[XFN]]

|-
| [[rel-contents|contents]]
| allowed
| allowed
| Refers to a document serving as a table of contents. Some user agents also support the synonym ToC (from "Table of Contents").
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-copyright|copyright]]
| allowed
| allowed
| Refers to a copyright statement for the current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-co-resident|co-resident]]
| not allowed
| external relation
| the referenced person lives in the same residence as the person represented by the current document
| [[XFN]]

|-
| [[rel-co-worker|co-worker]]
| not allowed
| external relation
| the referenced person is a co-worker of the person represented by the current document
| [[XFN]]

|-
| [[rel-crush|crush]]
| not allowed
| external relation
| this person considers the referenced person to be a crush (i.e. has a crush on the referenced person)
| [[XFN]]

|-
| [[rel-date|date]]
| not allowed
| external relation
| this person considers the referenced person to be a date (i.e. is dating the referenced person)
| [[XFN]]

|-
| [[rel-friend|friend]]
| not allowed
| external relation
| the person represented by the current document considers the person represented by the referenced document to be a friend
| [[XFN]]

|-
| [[rel-glossary|glossary]]
| allowed
| allowed
| Refers to a document providing a list of terms and their definitions that pertain to the current document.||[http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-help|help]]
| allowed
| allowed
| Refers to a document offering help (more information, links to other sources information, etc.)
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-its-rules|its-rules]]
| allowed
| not allowed
| Refers to a document with external ITS rules.
| [http://www.w3.org/TR/its20/#selection-global-html5 Internationalization Tag Set (ITS) Version 2.0]

|-
| [[rel-kin|kin]]
| not allowed
| external relation
| the referenced person is part of the extended family of the person represented by the current document
| [[XFN]]

|-
| [[rel-license|license]]
| allowed
| allowed
| …indicates that the <nowiki>[referenced document]</nowiki> is a license for the current page.
| [[rel-license]]

|-
| [[rel-me|me]]
| external relation
| external relation
| the referenced document represents the same person as does the current document
| [[XFN]]

|-
| [[rel-met|met]]
| not allowed
| external relation
| this person has met the referenced person
| [[XFN]]

|-
| [[rel-muse|muse]]
| not allowed
| external relation
| the referenced person inspires the person represented by the current document
| [[XFN]]

|-
| [[rel-neighbor|neighbor]]
| not allowed
| external relation
| the referenced person lives nearby the person represented by the current document
| [[XFN]]

|-
| [[rel-next|next]]
| external relation
| external relation
| Refers to the next document in a linear sequence of documents. User agents may choose to preload the "next" document, to reduce the perceived load time.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-nofollow|nofollow]]
| not allowed
| external relation
| indicates that the destination of that hyperlink {{should-not}} be afforded any additional weight or ranking by user agents which perform link analysis upon web pages (e.g. search engines).
| [[rel-nofollow]]

|-
| [[rel-parent|parent]]
| not allowed
| external relation
| the referenced person is a parent of the person represented by the current document
| [[XFN]]

|-
| [[rel-prev|prev]]
| external relation
| external relation
| Refers to the previous document in an ordered series of documents. Some user agents also support the synonym "Previous".
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-previous|previous]]
| external relation
| external relation
| Synonym of <code>prev</code>
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-section|section]]
| allowed
| allowed
| Refers to a document serving as a section in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-sibling|sibling]]
| not allowed
| external relation
| the referenced person is a sibling of the person represented by the current document
| [[XFN]]

|-
| [[rel-spouse|spouse]]
| not allowed
| external relation
| the referenced person is a spouse of the person represented by the current document
| [[XFN]]

|-
| [[rel-start|start]]
| allowed
| allowed
| Refers to the first document in a collection of documents. This link type tells search engines which document is considered by the author to be the starting point of the collection.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-stylesheet|stylesheet]]
| external resource
| not allowed
| a style sheet for the current document used with the invisible <link href> element which is not ideal for content relationships. Content relationships should be user visible and thus uses with <a href> are strongly preferred. Unfortunately the use of stylesheet in user visible content like <a href> appears to be strictly theoretical.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-subsection|subsection]]
| allowed
| allowed
| Refers to a document serving as a subsection in a collection of documents.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-sweetheart|sweetheart]]
| not allowed
| external relation
| this person considers the referenced person to be their sweetheart
| [[XFN]]

|-
| [[rel-tag|tag]]
| not allowed
| allowed
| …indicates that the <nowiki>[referenced document]</nowiki> is an author-designated "tag" (or keyword/subject) for the current page.
| [[rel-tag]]

|-
| [[rel-toc|toc]]
| allowed
| allowed
| Synonym of <code>contents</code> (from "Table Of Contents")
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4 Link types]

|-
| [[rel-transformation|transformation]]
| allowed
| allowed
| Relates a source document to a transformation, usually represented in XSLT, that relates the source document syntax to the RDF graph syntax. Used in [[grddl|GRDDL]]
| [http://www.w3.org/TR/grddl/#transformation GRDDL]

|}

=== notes ===
*<code>rel="alternate"</code> can take further meaning from additional attributes, such as
** <code>rel="alternate" lang="fr"</code> (French language version of this page)
** <code>rel="alternate" media="print"</code> (printable version of this page)
** <code>rel="alternate" media="handheld"</code> (version of the page intended or better for handheld/portable devices like PDAs, cell phones, etc.)

*Synonyms such as "previous", "toc" are not as widely supported as the main term.

== proposals ==
A few rel values have been developed as drafts as a result of going through most of the microformats [[process]], and are thus listed here for your serious consideration. You may use these values, and if you find any problems with them please point them out on the respective "issues" page for the rel value.

{| border="1"
|+
! rel value !! summary !! proposed in !! external spec (if any)
|-
| [[rel-pronunciation|pronunciation]] || …indicates that the destination of the 'link' element is a document providing a pronunciation lexicon for speech-synthesis purposes. || [[rel-pronunciation]]
|-
| [[rel-directory|directory]] || …indicates that the destination of the hyperlink is a directory listing containing an entry for the current page. || [[rel-directory]]
|-
| [[rel-enclosure|enclosure]] || …indicates that the destination of that hyperlink is intended to be downloaded and cached. || [[rel-enclosure]] || [http://www.apps.ietf.org/rfc/rfc4287.html RFC4287]
|-
| [[rel-home|home]] || …indicates that the <nowiki>[referenced document]</nowiki> is the homepage of the site in which the current page appears. || [[rel-home]]
|-
| [[rel-payment|payment]] || …indicates that the destination of the hyperlink provides a way to show or give support (e.g. financial) for the current page|| [[rel-payment]]
|}

== Metadata namespace declarations ==
Some rel values have been added to this page in the table about HTML5 features, but no examples, nor an actual specification explicitly stating that the value(s) should be used could be found. They are listed here after the indication of more specific/precise URLs to examples or specifications about them (preferably both). As the URLs to examples/specs have been provided, the values should no longer considered purely theoretical and advised for use.

{| border="1"
|+
! rel value !! summary !! source
|-
| schema.DC || a specification of all metadata terms maintained by the Dublin Core Metadata Initiative, with regard to the fifteen terms of the Dublin Core Metadata Element Set already published || [http://www.dublincore.org/documents/dcq-html/ Dublin Core]

|-
| schema.DCTERMS || a specification of all metadata terms maintained by the Dublin Core Metadata Initiative, reflecting the changes described more fully in the 2012 document "Maintenance changes to DCMI Metadata Terms" [http://dublincore.org/usage/decisions/2012/dcterms-changes/] || [http://www.dublincore.org/documents/dcq-html/ Dublin Core]
|-
|}

Notes:
* Dublin Core. This search may help: [http://www.google.co.uk/search?as_q=rel%3Dschema.*&hl=en&num=10&btnG=Google+Search&as_epq=&as_oq=&as_eq=&lr=&as_ft=i&as_filetype=&as_qdr=all&as_occt=any&as_dt=i&as_sitesearch=http%3A%2F%2Fdublincore.org&as_rights=&safe=images].
** '''examples from that search only use invisible <code><link href></code> element'''. At first glance it appears the results from the search show only uses with the invisible <code><link href></code> element which is not ideal for content relationships. Content relationships should be user visible and thus uses with <code><a href></code> are strongly preferred.
*** [http://www.ietf.org/rfc/rfc2731.txt RFC2731] defines <code>rel="schema.AC"</code> and <code>rel="schema.RC"</code> with the pattern <code>rel="schema.PREFIX"</code> as a syntax for defining namespaces for use in meta[@name], *[@rel], *[@rev] and (as per eRDF) *[@class] attributes. A link to a Dublin Core metadata schema is generally not suitable for end users, so <code><link href></code> appears to be more appropriate than <code><a href></code> for those that use Dublin Core metadata schemas.
*** The scheme proposed above provides metadata namespace declarations. As described by DCMI specifications, such indications '''cannot''' be provided w/o a suitable namespace. In order to give complete pieces of information, the correct description set must be: <code><link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"></code> (for the namespace declaration, followed by) <code><meta name="DCTERMS.<nowiki>[element]</nowiki>" content="<nowiki>[element.value]</nowiki>"></code> for related elements.
**** Note: [http://purl.org/dc/terms/ schema.DCTERMS] is conventionally related to an upgraded elements list than [http://purl.org/dc/elements/1.1/ schema.DC] and should be preferred as rel values. Both are discussed here for subject completeness)
** '''proposal to use in content currently only theoretical'''. Thus unfortunately the use of Dublin Core in user visible content like <code><a href></code> appears to be strictly theoretical. See [http://microformats.org/discuss/mail/microformats-discuss/2008-January/011445.html microformats-discuss/2008-January/011445.html] for a proposal to use Dublin Core in user visible content.
*** '''recent improvements'''. DCMI solves some trouble concerning metadata through the ''description set model''. Some of these informations cannot currently be provided in any standard ways other than DC, namely dates, validity and periodicity. Following this public bug report ([https://www.w3.org/Bugs/Public/show_bug.cgi?format=multiple&id=22520]), the correct namespace declaration for DC and DCTERMS metadata are now considered valid HTML code. We '''must''' encourage this practice both for internal usefulness and for shared practices.

* The Dublin Core document [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] is a specification for, and gives examples of, both <link rel="schema.DC" href="http://purl.org/dc/elements/1.1/"> and <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/">. Note that Dublin Core encourages the use of DCTERMS elements over DC. A list of projects which use Dublin Core metadata is maintained [http://dublincore.org/projects/ here].
* [http://dublincore.org/documents/dc-html/ "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"] also includes examples of <link rel="DCTERMS.[element]" href="">, where [element] = subject, isReferencedBy, creator, and publisher. The <link> tag is used instead of the <meta> tag whenever the content is a URL. (Note that this use is different from, but related to, <link rel="schema.DCTERMS" href="">.) Potentially, ''any'' of the 55 DCTERMS elements could be used in this way, and this could include use in HTML 5.
** As said before, HTML5 validators now allow the use of <code><link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"></code> for namespace declarations.

== brainstorming ==
Several rel values are being brainstormed as potential microformats and are thus listed here. If you find you have a use for such semantics in real world examples, consider trying out these values and provide feedback on the respective brainstorming page(s) with your results and experiences.

You may list new proposed rel values here, and even better if you can list and link to POSH uses in the wild.

{| border="1"
|+
! rel value !! summary !! brainstormed in and usage in the wild

|-
| [[rel-accessibility|accessibility]] || indicate[s] that the destination of that hyperlink contains accessibility information for the current page. || [http://www.brucelawson.co.uk/2009/rel-accessibility/ blog post] which itself uses the rel value in a <link> tag in the head of the document.

|-
| [[rel-author|author]] || indicate[s] that the destination of that hyperlink represents the author of the current page. Combines with [[rel-me|rel-me]] to chain authorship information. || Google has said it will index rel-Author in this [http://googlewebmastercentral.blogspot.com/2011/06/authorship-markup-and-web-search.html blog post], with further [http://www.google.com/support/webmasters/bin/answer.py?answer=1229920 discussion of the rel-me connection] See also [http://dev.w3.org/html5/spec/Overview.html#link-type-author the HTML5 spec]

|-
| [[rel-bibliography|bibliography]] || indicate[s] that the destination of that hyperlink is a bibliography for the current page. || [http://microformats.org/discuss/mail/microformats-discuss/2007-October/010863.html mailing list post, 2007-10-15]

|-
| [[rel-cite|cite]] || indicate[s] that the destination of that hyperlink is an authoritative source or a precedent to the current page. || [[distributed-conversation-brainstorming]]

|-
| [[rel-group|group]] || the referenced document represents a group to which the person represented by the current document belongs || [[group-brainstorming]]

|-
| [[rel-jslicense|jslicense]]
| Refers to a document with JavaScript source code and license information (also called a [http://www.gnu.org/licenses/javascript-labels.html JavaScript License Web Labels] page). We might want choose a keyword for this that is more general -- there are many situations besides JavaScript in which it is desirable or required by license agreements (e.g., GNU GPL) to make an offer of both the source code and a copy of a license when distributing object code versions of a given work.
|* Brainstorming page -- thoughts on the name?
* Ex. [http://www.eff.org EFF.org] (on <code>link</code>)
* Ex. [http://www.fsf.org FSF.org] (on <code>a</code>)
|-
| [[rel-longdesc|longdesc]] || Alternative to the img longdesc attribute, for use on visible links || [http://www.google.com/search?q=rel%3D%22longdesc%22 Google search for rel=longdesc in the wild] shows many sources of proposals. Please edit this to list the earliest and perhaps most recent/comprehensive proposal. No known real world POSH usage in the wild yet.

|-
| [[rel-map|map]] || Link to a map. Possibly embedded within an adr, hCard, geo or hCalendar. Parsers {{may}} attempt to parse the URL if it is a link to a known map site (e.g. Geohash, Google Maps, Multimap) and extract co-ordinates and other useful data. || (to [[User:TobyInk|TobyInk]] by email)

|-
| [[rel-member|member]] || the referenced document represents a member of the group represented by the current document || [[group-brainstorming]]

|-
| [[rel-profile|profile]] || indicate[s] that the destination of that hyperlink is a metadata profile (e.g. an [[XMDP]] profile) for the current page or portion thereof || [[xmdp-brainstorming]]

|-
| [[rel-shortlink|shortlink]] || the referenced document represents the current document but with a shorter URL || [http://samj.net/2009/04/introducing-relshort-better-alternative.html blog post]

|-
| vcalendar-parent || link from an event to a containing event || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]
|-
| vcalendar-child || link from an event to a contained event || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]
|-
| vcalendar-sibling || link from an event to a related event with the same container || [[User:TobyInk/hcalendar-1.1|hCalendar 1.1 draft]]

|-
| [[rel-status|status]] || the referenced document represents the status (or source of status updates) for the author of this document || [http://monkinetic.com/2009/11/24/status-autodiscovery-relstatus.html blog post]

|}

=== more brainstorming ===
See also:
* [[genealogy-brainstorming]] for some thoughts on possible additional values for family relationships (use existing [[XFN]] [[rel-parent|parent]], [[rel-child|child]], [[rel-sibling|sibling]], [[rel-spouse|spouse]], [[rel-kin|kin]] values first though)
* [[xpn-brainstorming]] for some thoughts on possible additional values for professional relationships (use existing [[XFN]] [[rel-co-worker|co-worker]], [[rel-colleague|colleague]] values first though)

== POSH usage ==
There are numerous rel values used as [[POSH]], both in the wild, whose origins are not necessarily known, nor are their meanings consistent. There are also numerous rel values from external proposals of varying degrees of merit. It is useful to document their existence and summarize their implied meanings/usage intent as research that may be used to perhaps take one or more of them thru the microformats [[process]] if there is both sufficient interest and sufficient in the wild usage.

Note: If a value is missing from this table, it may have either already been promoted by writing it up as a proposal, or demoted by being explicitly dropped. Please check the other tables first before adding to this table.

Note: this list is incomplete, please help complete it from the following sources:

External sources:
* [http://developer.mozilla.org/about/meta Meta Information in DevMo Docs] (DevMo)
* [http://wiki.mozilla.org/Microsummaries Microsummary]
* [http://lachy.id.au/dev/markup/specs/wclr/ Web Communication Link Relationships] (WCLR)
* [http://www.w3.org/MarkUp/Relationships.html W3C Link Relationship values draft] (LRdraft) - from a draft of the HTML spec circa 1991.
* [http://www.whatwg.org/specs/web-apps/current-work/multipage/section-links.html#linkTypes HTML5 draft] '''Liable to change'''
* [http://wiki.foaf-project.org/Autodiscovery FOAF Project Wiki: Autodiscovery] (FOAF)
* [http://www.apps.ietf.org/rfc/rfc4685.html RFC4685]
* [http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html Google Blog]

{| border="1"
|+
! rel value !! summary !! origin !! proposal(s)

|-
| [[rel-archive|archive]] || index of archived entries || unknown, perhaps Wordpress open source blogging software || WCLR

|-
| [[rel-archives|archives]] || Provides a link to a collection of records, documents, or other materials of historical interest. || || HTML5

|-
|[[rel-author|author]]||see brainstorming above for suggested use by google||unknown || DevMo / HTML5

|-
| [[rel-canonical|canonical]] || To help search engines disambiguate the same page with multiple representations || Google || [http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html Google]/[http://www.bing.com/community/blogs/webmaster/archive/2009/02/12/partnering-to-help-solve-duplicate-content-issues.aspx Microsoft]/[http://www.ysearchblog.com/2009/02/12/fighting-duplication-adding-more-arrows-to-your-quiver/ Yahoo!], [http://blog.ask.com/2009/02/ask-is-going-canonical.html Ask Jeeves]

|-
| [[rel-comment|comment]] || … || … || WCLR

|-
| [[rel-contribution|contribution]] || … || … || WCLR

|-
| [[rel-edituri|EditURI]]
| Location of the xml-rpc gateway for a Wordpress install that allows external programs to add, edit and delete posts. Used by "[http://codex.wordpress.org/Weblog_Client WordPress blog client]" software for automating posting and updating blog content from your desktop. || Seen in [http://www.wordpress.org/ WordPress], e.g. [http://www.tom-watson.co.uk/]. || Description stubbed in [[rel-edituri]].

|-
| [[rel-endorsed|endorsed]] || … || … || WCLR

|-
| [[rel-fan|fan]] || xxxx. || … || [[hcard-user-profile-authoring]]

|-
| [[rel-feed|feed]] || Gives the address of a syndication feed for the current document. || … || WCLR/ HTML5

|-
| [[rel-footnote|footnote]] || Location of the footnote on a link to a footnote. || Markdown preprocessors such as [http://maruku.rubyforge.org/ Maruku] || HTML5

|-
| [[rel-icon|icon]] || Imports an icon to represent the current document. (Allowed in <code>link</code> only) || [http://dev.w3.org/html5/spec-LC/links.html#rel-icon HTML5] || WCLR/HTML5

|-
| [[rel-kinetic-stylesheet|kinetic-stylesheet]] || Imports a [http://kssproject.org/ KSS] 'kinetic stylesheet' to bind dynamic behavior to elements || Used in the [http://plone.org Plone] Content Management System || …

|-
| [[rel-lightbox|lightbox]] || Hook - Indicates that following the link will trigger a "lightbox" script (Allowed in <code>link</code> only) || ([http://www.google.co.uk/search?q=rel%3D%22lightbox%22 Google search for rel=lightbox in the wild]) || …

|-
| [[rel-lightbox|lightbox[group_name]]] || Used by lightbox scripts to group different sets of images together. Images from one group will not appear in another group's lightbox. See also "lightbox". || [http://lokeshdhakar.com/projects/lightbox2/#how Lightbox 2] || …

|-
| [[rel-prettyPhoto|prettyPhoto]] || See also "lightbox" || ([http://www.google.fr/search?q=rel%3D%22prettyphoto%22 Google search for rel="prettyphoto" in the wild]) || …

|-
| [[rel-clearbox|clearbox]] || See also "lightbox" || ([http://www.google.fr/search?q=rel%3D%22clearbox%22 Google search for rel="clearbox" in the wild]) || …

|-
| [[rel-made|made]] || … || … || LRdraft

|-
| [[rel-meta|meta]] || … || [http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/#transport 1999 W3C RDF syntax REC] || FOAF

|-
| [[rel-microsummary|microsummary]]|| … || … ||[http://wiki.mozilla.org/Microsummaries Microsummary], be aware of: [[page-summary-formats#Issues_2|microsummary issues]]

|-
| [[rel-noreferrer|noreferrer]] || indicates that no referrer information is to be leaked when following the link. || [http://dev.w3.org/html5/spec-LC/links.html#rel-noreferrer HTML5] || HTML5

|-
| [[rel-openid-delegate|openid.delegate]] || … || ([http://www.google.co.uk/search?q=%22rel%3Dopenid%22 Google search for rel=openid.* in the wild]) || …

|-
| [[rel-openid-server|openid.server]] || … || ([http://www.google.co.uk/search?q=%22rel%3Dopenid%22 Google search for rel=openid.* in the wild]) || …

|-
| [[rel-permalink|permalink]] || … || … || WCLR

|-
| [[rel-pgpkey|pgpkey]] || (see also rel-publickey) || … || [http://golem.ph.utexas.edu/~distler/blog/archives/000320.html], [http://golem.ph.utexas.edu/~distler/blog/archives/000325.html]

|-
| [[rel-pingback|pingback]] || Gives the address of the pingback server that handles pingbacks to the current document. (Allowed in <code>link</code> only) || … || WCLR/ HTML5

|-
| [[rel-popover|popover]] || Used by a JS widget to display a large, descriptive tooltip. || [http://twitter.github.com/bootstrap Twitter's Bootstrap] [http://twitter.github.com/bootstrap/javascript.html#popovers Popover.js] || …

|-
| [[rel-prefetch|prefetch]] || Specifies that the target resource should be pre-emptively cached. (Allowed in <code>link</code> only) || … || HTML5

|-
| [[rel-publickey|publickey]] || (see also rel-pgpkey) || … || [http://rasterweb.net/raster/2002/12/12/20021212072812/]

|-
| [[rel-publisher|publisher]] || Connecting the website of a publisher with their G+ profile || Google || [http://support.google.com/webmasters/bin/answer.py?answer=1708844]

|-
| [[rel-referral|referral]] || … || … || WCLR

|-
| [[rel-related|related]] || … || … || WCLR

|-
| [[rel-replies|replies]] || indicates a continued thread || unknown || [http://www.apps.ietf.org/rfc/rfc4685.html RFC4685]

|-
| [[rel-resource|resource]] || … || … || WCLR

|-
| [[rel-search|search]] || … || unknown || unknown

|-
| [[rel-sitemap|sitemap]] || Links to a site map document. || … || http://www.sitemaps.org/

|-
| [[rel-sponsor|sponsor]] || … || … || WCLR

|-
| [[rel-tooltip|tooltip]] || Used by a JS widget to display a tooltip similar (though more customizable) to what is shown by browsers if the 'title' attribute is present. || [http://twitter.github.com/bootstrap Twitter's Bootstrap] [http://twitter.github.com/bootstrap/javascript.html#tooltips Tooltip.js] (and likely other JS tools) || …

|-
| [[rel-trackback|trackback]] || … || unknown, perhaps open source Movable Type blogging software || WCLR

|-
| [[rel-unendorsed|unendorsed]] || (probably redundant to [[rel-nofollow|nofollow]]) || … || WCLR

|-
| [[rel-user|user]] || … || … || WCLR
|-
| [[rel-wlwmanifest|wlwmanifest]] || Used by "[http://explore.live.com/windows-live-writer Windows Live Writer]," a Microsoft [http://codex.wordpress.org/Weblog_Client blog client] for automating posting and updating blog content from your desktop. || Seen in [http://www.wordpress.org/ WordPress], e.g. [http://www.tom-watson.co.uk/]. Similar values are probably used by other blog content management systems as well. || …

|}

=== WCLR ===

The WCLR proposal is described by its author (in e-mail, 2007-09-25) as:

<blockquote>
…now effectively obsolete, since HTML5 and Microformats cover all the worthwhile relationships in that already.

These are [http://www.whatwg.org/specs/web-apps/current-work/multipage/section-links.html#linkTypes covered by HTML5 already]:

* permalink -> bookmark
* archive -> archives
* feed
* pingback
* unendorsed -> nofollow

The rest now seem unnecessary.
</blockquote>

Nonetheless, there may be some mileage in using them in microformats, at least until HTML5 is widely available.

== HTML5 link type extensions ==

The following values are registered as link type extensions per the [http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#other-link-types requirements in the WHATWG HTML spec] and the [http://dev.w3.org/html5/spec/links.html#other-link-types requirements in the W3C HTML5 spec].

Before you register a new value:
* '''Please check the [[#formats|Formats table]] and DO NOT re-register''' rel values that are already there. Please note that the W3C HTML WG has made a [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Decision] to drop <code>index</code>, <code>up</code>, <code>first</code> and <code>last</code> from the HTML5 spec itself.
* '''Please check the [[#dropped|Dropped table]] and DO NOT register''' values that are already there. If you believe a rel value was dropped from another specification without prejudice, please provide link/cite to explicit text/decision stating as such, e.g. the value was merely postponed, or perhaps expected to be spun-out into its own spec from the group developing that specification.

Note that entries in the [[#formats|Formats table]] and entries that are already in HTML5 as built-in keywords are also considered extensions with the "Ratified" status.

Please make sure that registrations added here have all the required data filled in ''including'':
* "Effect on link"
* "Effect on a and area" and
* a link to a spec that documents the keyword ''as an HTML <code>rel</code> keyword''. (A spec that merely defines the file format of the link target but does not define the <code>rel</code> keyword for use in HTML is not the kind of spec that is being required here.)

Entries lacking any of the above required data will likely be removed.

Changes to this registry may not be reflected in validators in real time.

{| border="1"
|+
! Keyword
! Effect on <code>link</code>
! Effect on <code>a</code>, <code>area</code>
! Brief description
! Link to specification
! Synonyms
! Status

|-
| [[rel-apple-touch-icon|apple-touch-icon]]
| External Resource
| Not allowed
| Specify a Webpage Icon for a “Web Clip”, or “touch icon”, for mobile devices (not limited to Apple devices).
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| probably redundant with rel=icon
| proposed

|-
| [[rel-apple-touch-icon-precomposed|apple-touch-icon-precomposed]]
| External Resource
| Not allowed
| Specify a Webpage Icon for a “Web Clip”, or “touch icon”, for mobile devices (not limited to Apple devices).
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| probably redundant with rel=icon
| proposed

|-
| [[rel-apple-touch-startup-image|apple-touch-startup-image]]
| External Resource
| Not allowed
| Specify a splashscreen for Web apps on iOS Safari
| [http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/configuringwebapplications/configuringwebapplications.html Apple's Safari Web Content Guide]
| maybe redundant with rel=icon with the sizes attribute?
| proposed

|-
| [[rel-attachment|attachment]]
| Hyperlink
| Hyperlink
| The resource linked to is "attached" to this document, similar to email attachments. Used in WordPress.
| No formal specification
|
| proposed

|-
| [[rel-canonical|canonical]]
| External Resource
| Not allowed
| Specifies the canonical URL for the current document in order to help avoid duplicate content.
| [http://en.wikipedia.org/wiki/Canonical_meta_tag Canonical meta tag] [http://www.Google.com/support/webmasters/bin/answer.py?answer=139066#2 Canonicalization at Google Webmaster Central] [http://www.Bing.com/community/site_blogs/b/webmaster/archive/2009/02/12/partnering-to-help-solve-duplicate-content-issues.aspx Microsoft Webmaster Center] [http://www.YSearchBlog.com/2009/02/12/fighting-duplication-adding-more-arrows-to-your-quiver/ Yahoo! Search Blog]
|
| proposed

|-
| [[rel-category|category]]
| Hyperlink
| Hyperlink
| Refers to a category assigned to the current document or post. Implemented by WordPress for indicating a relation between a blog post and a category.
| [[rel-category]]
|
| proposed

|-
| [[rel-component|component]]
| External Resource
| Not allowed
| Specify an HTML document that is treated as a component of this document.
| [https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/components/index.html Web Components]
|
| proposed

|-
| [[rel-disclosure|disclosure]]
| Not allowed
| External Resource
| The 'disclosure' Link Relation Type designates a list of patent disclosures or a particular patent disclosure itself made with respect to material for which such relation type is specified.
| [http://tools.ietf.org/html/draft-yevstifeyev-disclosure-relation The 'disclosure' Link Relation Type]
|
| proposed

|-
| [[rel-discussion|discussion]]
| Hyperlink
| Hyperlink
| Refers to discussion of the current document or post.
| [[rel-discussion]]
|
| proposed

|-
| [[rel-dns-prefetch|dns-prefetch]]
| External Resource
| Not allowed
| Tells the browser to perform dns lookup for host names ahead of use.
| [https://developer.mozilla.org/En/Controlling_DNS_prefetching Mozilla documentation] [http://dev.chromium.org/developers/design-documents/dns-prefetching Google documentation]
|
| proposed

|-
| [[rel-edituri|EditURI]]
| External Resource
| Not allowed
| A blogging auto discovery value, commonly used by WordPress
| [http://bitworking.org/projects/atom/draft-gregorio-09.html#Edit AtomAPI]
|
| proposed

|-
| [[rel-entry-content|entry-content]]
| Not allowed
| External Resource
| Indicates that the referenced document is an alternative display source for an Internet Explorer Web Slice.
| [http://msdn.microsoft.com/en-us/library/cc304073(VS.85).aspx#_alternative Web Slice format specification 0.9]
|
| proposed

|-
| [[rel-external|external]]
| Not allowed
| Hyperlink
| Indicates that the referenced document is not part of the same site as the current document.
| [[rel-external]]
|
| proposed

|-
| [[rel-home|home]]
| Hyperlink
| Hyperlink
| Refers to the top level document for the current document. It can be combined with 'alternate' to indicate a feed for the site of the current page.
| [[rel-home]]
|
| proposed

|-
| [[rel-hub|hub]]
| Hyperlink
| Hyperlink
| Refers to a hub that enables registration for notification of updates to the current page.
| [http://pubsubhubbub.googlecode.com/svn/trunk/pubsubhubbub-core-0.3.html#discovery PubSubHubbub Spec]
|
| proposed

|-
| [[rel-in-reply-to|in-reply-to]]
| Hyperlink
| Hyperlink
| Refers to an original post that the current page is a comment on or reply to.
| [[rel-in-reply-to]]
|
| proposed

|-
| [[rel-index|index]]
| Hyperlink
| Hyperlink
| Refers to a document providing a list of topics with pointers that pertain to the current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
|
| proposed

|-
| [[rel-issues|issues]]
| Hyperlink
| Hyperlink
| Refers to issues regarding the current document or specification.
| [[rel-discussion]]
|
| proposed

|-
| [[rel-lightbox|lightbox]]
| Not allowed
| Img Pop-Up
| Images with this attribute are displayed in a larger way than embedded in a website (or how you specified it) when clicked (e.g. with installed "Lightbox 2"-Plugin). When adding [group] to rel="lightbox" all images get a clickable button for next/prev; insert into <code><a rel="lightbox[group]"><img src="http:example.com/img.jpg"></a></code>
| [http://lokeshdhakar.com/projects/lightbox2/ Lightbox 2] (needs actual specification to be kept in this list, this link is just documentation of one implementation)
|
| proposed

|-
| [[rel-meta|meta]]
| External Resource
| Not allowed
| External metadata about the HTML document
| [http://www.w3.org/TR/rdf-syntax-grammar/#section-rdf-in-HTML W3C's RDF/XML Syntax Specification]
|
| proposed

|-
| [[rel-openid.delegate|openid.delegate]]
| External Resource
| Not allowed
| When the page that contains the link is used as an OpenID indentifier, the relying party perform sOpenID 1.1 authentication with the link target as the identifier instead.
| [http://openid.net/specs/openid-authentication-1_1.html#delegating_authentication OpenID Authentication 1.1]
|
| proposed

|-
| [[rel-openid.server|openid.server]]
| External Resource
| Not allowed
| The OpenID server for the relying party to contact for OpenID 1.1 authentication
| [http://openid.net/specs/openid-authentication-1_1.html#anchor4 OpenID Authentication 1.1]
|
| proposed

|-
| [[rel-openid2.local_id|openid2.local_id]]
| External Resource
| Not allowed
| When the page that contains the link is used as an OpenID indentifier, the relying party perform sOpenID 2.0 authentication with the link target as the identifier instead.
| [http://openid.net/specs/openid-authentication-2_0.html#rfc.section.7.3.3 OpenID Authentication 2.0]
|
| proposed

|-
| [[rel-openid2.provider|openid2.provider]]
| External Resource
| Not allowed
| The OpenID server for the relying party to contact for OpenID 2.0 authentication
| [http://openid.net/specs/openid-authentication-2_0.html#rfc.section.7.3.3 OpenID Authentication 2.0]
|
| proposed

|-
| [[rel-p3pv1|p3pv1]]
| External Resource
| Not allowed
| References a machine-readable privacy policy description in the P3P format
| [http://www.w3.org/TR/P3P/#syntax_link P3P spec]
|
| proposed

|-
| [[rel-pgpkey|pgpkey]]
| External Resource
| Not allowed
| Associates a PGP key with a Web page so that the Web page URL can be used as the commenter's URL in PGP-signed blog comments and the blogging system receiving the comment can fetch the key and verify the signature as belonging to the owner of the URL.
| [http://golem.ph.utexas.edu/~distler/blog/archives/000320.html PGP-Signed Comments]
|
| proposed

|-
| [[rel-pingback|pingback]]
| External Resource
| Not allowed
| gives the address of the pingback server that handles pingbacks to the current document
| [http://www.hixie.ch/specs/pingback/pingback Pingback]
|
| proposed

|-
| [[rel-prerender|prerender]]
| External Resource
| Not allowed
| Prerenders the Web page targeted by the link including running it scripts.
| [http://dev.chromium.org/developers/design-documents/prerender Chrome Prerendering]
|
| proposed

|-
| [[rel-profile|profile]]
| External Resource
| Contextual External Resource
| indicate[s] that the destination of that hyperlink is a metadata profile (e.g. an [[XMDP]] profile) for the current page or portion thereof. See also [[xmdp-brainstorming]].
| [http://microformats.org/wiki/rel-profile rel-profile]
|
| proposed

|-
| [[rel-rendition|rendition]]
| External Resource
| External Resource
| Indicates some example rendering, interpretation, or depiction of the source. User agents may choose to execute, display, or render the target in-place; or navigate to the target.
| [http://www.globalmentor.com/specs/html-rel-rendition/ HTML rel rendition]
|
| proposed

|-
| [[rel-service|service]]
| External Resource
| Not allowed
| Atom Publishing Protocol editing service autodiscovery.
| [http://wiki.whatwg.org/wiki/ServiceRelExtension Documentation on the WHATWG wiki]
|
| proposed

|-
| [[rel-shortlink|shortlink]]
| External Resource
| Not allowed
| Specifies the preferred shortened URL for the page.
| [http://code.google.com/p/shortlink/wiki/Specification shortlink spec]
|
| proposed

|-
| [[rel-sidebar|sidebar]]
| Hyperlink
| Hyperlink
| Indicates that the referenced document is intended to be shown in a secondary browsing context.
| [[rel-sidebar]]
|
| proposed

|-
| [[rel-sitemap|sitemap]]
| External Resource
| Not allowed
| Provides a link to an XML document describing the layout of the site.
| [[rel-sitemap]]
|
| proposed

|-
| [[rel-syndication|syndication]]
| Hyperlink
| Hyperlink
| Refers to a page which is a syndicated copy of the current page.
| [[rel-syndication]]
|
| proposed

|-
| [[rel-timesheet|timesheet]]
| External Resource
| Not allowed
| Applies a timesheet to the document.
| [http://www.w3.org/TR/timesheets/#smilTimesheetsNS-Elements-Timesheet non-normative section in the Timesheet spec]
|
| proposed

|-
| [[rel-widget|widget]]
| External Resource
| External Resource
| Autodiscovery for W3C widgets
| [http://dev.w3.org/2006/waf/widgets/Overview.html#linking-to-a-widget-package-from-a-html- non-normative section in the Widget packaging spec]
|
| proposed

|-
| [[rel-wlwmanifest|wlwmanifest]]
| External Resource
| Not allowed
| Windows Live Writer manifest autodiscovery
| [http://msdn.microsoft.com/en-us/library/bb463263.aspx documentation on MSDN]
|
| proposed

|-
| [[rel-image_src|image_src]]
| External Resource
| Not allowed
| Specify a Webpage Icon for use by Facebook, Yahoo, Digg, etc.
| Unknown, but see for instance [http://www.niallkennedy.com/blog/2009/03/enhanced-social-share.html this]
| probably redundant with rel=icon
| proposed

|-
| [[rel-cmis-acl|http://docs.oasis-open.org/ns/cmis/link/200908/acl]]
| External Resource
| External Resource
| Identifies the resource containing a CMIS ACL document for the link context
| [http://docs.oasis-open.org/cmis/CMIS/v1.0/cs01/cmis-spec-v1.0.html#_Toc243905525 CMIS 1.0, Section 3.4.3.4]
|
| proposed

|-
| [[rel-stylesheet/less|stylesheet/less]]
| External Resource
| Not allowed
| Less CSS framework stylesheets.
| [http://lesscss.org/#-client-side-usage Less CSS usage]
|
| proposed

|}

== Use with HTTP Link Header ==
You can also use any of the rel values (that are allowed for link elements) with HTTP Link Headers,

Example: returning a Javascript file with a license (since JS itself has no way to indicate a license)
<source lang=text>
Link: <http://creativecommons.org/publicdomain/zero/1.0/>; rel="license"
</source>

For multiple licenses (e.g. CC-SA and GPL), simply use multiple <code>Link:</code> headers.
<source lang=text>
Link: <http://creativecommons.org/licenses/by-sa/3.0/>; rel="license"
Link: <http://www.gnu.org/licenses/gpl.html>; rel="license"
</source>

Example: similarly, linking to a copyright statement for an image:
<source lang=text>
Link: <http://example.org/copyright.html>; rel="copyright"
</source>
or providing a brief inline copyright statement:
<source lang=text>
Link: <data:text/plain;charset=utf-8,Copyright 2013 ExampleCo, All Rights Reserved.>; rel="copyright"
</source>

== non HTML rel values ==
There are markup languages other than HTML that also have a rel attribute, often based upon the HTML rel attribute.
It is useful to document some of these other languages and their rel values for both reference purposes, and to provide background research for the possible development and re-use of these values in HTML, as [[poshformats]] or [[microformats]]

Sources:
* [[Atom]] [[RFC4287]] specification.
* See http://www.iana.org/assignments/link-relations.html for more.
* See [http://amundsen.com/media-types/maze/format/#link-relations Maze+XML]
* See [http://amundsen.com/media-types/collection/format/#link-relations Collection+JSON]
* See [http://www.opensearch.org/Specifications/OpenSearch/1.1#Url_rel_values OpenSearch]
* See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

{| border="1"
|+
! rel value !! summary (from the relevant specification where possible)) !! defining specification

|-
| self
| From http://www.ietf.org/rfc/rfc4287.txt : <blockquote>The value "self" signifies that the IRI in the value of the href attribute identifies a resource equivalent to the containing element.</blockquote>
| [[Atom]] http://www.ietf.org/rfc/rfc4287.txt

|-
| http://gdata.youtube.com/schemas/2007#in-reply-to || See http://code.google.com/apis/youtube/2.0/developers_guide_protocol_comments.html || YouTube extension to Atom

|-
| collection || Refers to a resource which represents a collection of which the current resource is a member.

When used in the Maze+XML media type, the associated URI returns the available collection of mazes.
|| Maze+XML, Collection+JSON, OpenSearch

|-
| east || Refers to a resource to the "east" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the east in the active maze.

|| Maze+XML

|-
| exit || Refers to a resource that represents the exit or end of the current client actvity or process.

When used in the Maze+XML media type, the associated URI points to the final exit resource of the active maze.

|| Maze+XML

|-
| north || Refers to a resource that is "north" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the north in the active maze.

|| Maze+XML

|-
| south || Refers to a resource that is "south" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the south in the active maze.

|| Maze+XML

|-
| [[rel-via|via]] || Identifies a resource that is the source of the information in the context. || Atom 1.0 Syndication format (RFC 4287)

|-
| west || Refers to a resource that is "west" of the current resource.

When used in the Maze+XML media type, the associated URI points to a neighboring cell resource to the west in the active maze.

|| Maze+XML

|-
| item || The target IRI points to a resource that is a member of a collection represented by the context IRI. || Collection+JSON

|-
| create-form || When included in a resource, the "create-form" link relation MAY identify a target resource that represents the form to append a new member to the link context. || See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

|-
| edit-form || When included in a resource, the "edit-form" link relation identifies a target resource that represents the form for editing associated resource. || See [http://tools.ietf.org/html/rfc6861 The Create-Form and Edit-Form Link Relations (RFC6861)]

|-
| lightframe || Opens the target in a lightbox. On inclusion it provides a simple target the lightframe and loads the content in a lightbox effect || Lightbox

|-
| superbox[image] || jQuery Superbox! is a script which allows you display windows with the lightbox effect. || superbox

|-
| wp-video-lightbox || wp-video-lightbox! is a rel to anchor tag script display videos with the lightbox effect. || wp-video-lightbox
|-
| ... || ... || ...

|}

== dropped ==
The following rel values were in earlier version(s) of specification(s) and it is presumed by their absence from the most recent version of the respective specification(s) that they have been deprecated or obsoleted.

In general, you {{should not}} use any dropped values.

If any such values have been superceded by standard values (see the first table on this page), then you {{must not}} use the dropped versions.

In particular:
* if a rel value was in a draft and is missing (without explanation) from the final spec, or
* if a rel value was in a previous version of and is missing (without explanation) from an update to the specification (even a draft update)

Then absent any other information or explanation, it is presumed that the group/editors working on that specification decided to explicitly drop it (either in development, or in the updated version) and thus it should be obsoleted (not re-registered).

If you wish to add them, please research why such values were omitted from latter specifications before doing so. If you do discover the reasoning, please add a short statement or link to thereof into the appropriate place in the following table.

If there is more data, e.g. a link to an email of discussion of the spec development that explains ''why'' the rel value was dropped, and it explicitly states, e.g. it was without prejudice, or merely post-poned, or perhaps expected to be spun-out into its spec (or some other explicit positive reason), then it makes to link/cite that explicit text as part of a proposal.

Sources:
* [http://www.w3.org/MarkUp/html3/ HTML3] (HTML3) / has been superceded by [http://www.w3.org/MarkUp/Wilbur/ HTML 3.2] - which itself has been superceded by [http://www.w3.org/TR/REC-html40 HTML 4.0] - which itself has been updated by [http://w3.org/TR/html401 HTML 4.01], commonly referred to as "HTML 4" in this wiki and other places.)
* [http://www.w3.org/TR/relations.html Proposed HTML 4.0 link types] (HTML4dropped) - obsoleted/superceded by the HTML 4.0 Recommendation. Any values that were in the "Proposed HTML 4.0 link types" document but didn't make it into the HTML 4.0 Recommendation were thus explicitly dropped and should be avoided.

{| border="1"
|+
! rel value !! summary !! defining specification !! why dropped

|-
|[[rel-banner|banner]]||Was used to reference another document to be used as banner for this document (i.e. a form of "include" statement).|| HTML3 ||unknown

|-
| [[rel-begin|begin]] || identifies the author-defined start of a sequence of documents of which the current document is a node.
|| HTML4dropped||unknown

|-
| [[rel-biblioentry|biblioentry]] || identifies a bibliographic entry || HTML4dropped||unknown

|-
| [[rel-bibliography|bibliography]] || identifies a bibliography || HTML4dropped||unknown

|-
| [[rel-child|child]] (obsolete/superceded) || the target document is a hierarchical child, or subdocument, of the current document|| HTML4dropped||unknown

|-
| [[rel-citation|citation]] || the target is a bibliographic citation || HTML4dropped||unknown

|-
| [[rel-collection|collection]] || the target document is an collection that contains the current document || HTML4dropped||unknown

|-
| [[rel-definition|definition]] || identifies a definition of a term || HTML4dropped||unknown

|-
| [[rel-disclaimer|disclaimer]] || identifies a hypertext link to a legal disclaimer || HTML4dropped||unknown

|-
| [[rel-editor|editor]] || identifies a hypertext link to an editor || HTML4dropped||unknown

|-
| [[rel-end|end]] || identifies the author-defined end of a sequence of documents of which the current document is a node. || HTML4dropped||unknown

|-
| [[rel-footnote|footnote]] || the anchor is a footnote marker and the target is a footnote || HTML4dropped||unknown

|-
| [[rel-navigate|navigate]] || the target document contains information such as a image map that will help users to gain a sense of how and where to found information || HTML4dropped||unknown

|-
| [[rel-origin|origin]] || synonym for <code>top</code> || HTML4dropped||unknown

|-
| [[rel-parent|parent]] (obsolete/superceded) || the target document is the hierarchical parent, or container, of the current document|| HTML4dropped||unknown

|-
| [[rel-pointer|pointer]] || the target is a pointer to the real target. This value can be used by a user agent to perform a pre-fetch of the specified target for evaluation until the real target is reached || HTML4dropped||unknown

|-
| [[rel-publisher|publisher]] || identifies a hypertext link to a publisher || HTML4dropped||unknown

|-
| [[rel-sibling|sibling]] (obsolete/superceded) || the target document is a child of a common parent, or a hierarchical peer of the current document|| HTML4dropped||unknown

|-
| [[rel-top|top]] || the target document is the logical top node of the tree (see also <code>begin</code>) || HTML4dropped||unknown

|-
| [[rel-trademark|trademark]] || identifies a hypertext link to a trademark notice || HTML4dropped||unknown

|-
| [[rel-translation|translation]] || the target is a translation to another language || HTML4dropped||unknown

|-
| [[rel-urc|urc]] || identifies a Universal Resource Citation || HTML4dropped||unknown

|-
|}

== dropped without prejudice ==
In one known instance (from HTML4 to HTML5), some rel values were in an earlier version of a specification (or a proposal) and were dropped from a latter (draft) version, and it was noted that these values were dropped with the intent that they could still be proposed in a registry and thus they explicitly were not deprecated or obsoleted. This section documents such values as separate from the [[#dropped|dropped]] section.

In general, you {{should not}} use any dropped values.

If any such values have been superceded by standard values (see the first table on this page), then you {{must not}} use the dropped versions.

Rel values that were dropped without prejudice from a specification will be considered similar to new values that have never been specified.

If you know of additional rel values that were dropped without prejudice from an update to a specification, please cite a URL and quote from the group developing the specification that officially states from that group that the dropping of the values was done without prejudice, or equivalent statement (such as explicit allowance of external registration, proposal, and/or development).

This table serves a historical purpose. If you wish to propose a value from this table, please copy it and leave it in place.

Sources:
* Several rel values were [http://www.w3.org/Bugs/Public/show_bug.cgi?id=7475#c15 explicitly dropped from HTML5]. Per: [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Issue 118 Decision] ('''emphasis''' added): <blockquote>"The final proposal argues for the removal of some relation values, to wit, it suggests removal of '''index, up, first and last'''. It was pointed out in survey comments that these relations are already registered in the IANA link relation registry. Presumably, '''these relations could also be entered in whatever other registry or registries HTML5 adopts for this purpose'''...."Next Steps..."Since the relations to be removed are already registered at the IANA link relation registry, no further action is needed to include them there. WG members are '''free to register or record these relations elsehwere''' [sic], as well."</blockquote>

{| border="1"
|+
! rel value
! summary
! defining specification
! why dropped

|-
| [[rel-first|first]]
| synonym for <code>begin</code>
| HTML4dropped - never in an official spec
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-index|index]]
| Refers to a document providing an index for the current document.
| was in [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-last|last]]
| synonym for <code>end</code>
| HTML4dropped - never in an official spec
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
| [[rel-up|up]]
|When the document forms part of a hierarchy, this link references the immediate parent of the current document.
| was in [http://www.w3.org/MarkUp/html3/dochead.html HTML3] - but [http://www.w3.org/TR/html401/types.html#type-links dropped in HTML4]
| [http://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html Explicitly dropped from HTML5 interim draft yet permitted for external registry]

|-
|}

See related [http://dev.w3.org/html5/spec/links.html#linkTypes HTML5: Link types] for existing HTML5 specified rel values.

== rejected ==
Some rel values have been proposed and rejected. They are listed here to make that explicit. Authors {{must not}} use rejected rel values.

Source: [[rejected-formats]].

{| border="1"
|+
! rel value !! origin / proposal !! why rejected
|-
| [[rel-logo|logo]]
| [http://relogo.org Relogo.org]
| [[rejected-formats#Logo]]
|-
|[[rel-pavatar|pavatar]] || [http://pavatar.com/ pavatar] || [[rejected-formats#Pavatar]]
|-
|}

== tools ==
See [[implementations]].

== addtional external research ==
Here are some additional historical references to the development or rel-values which may be useful when researching values, especially why specific values may have been proposed but abandoned.
* 1996-06-07 [http://www.w3.org/MarkUp/draft-ietf-html-relrev-00.txt Hypertext links in HTML] (copies: [http://ftp.ics.uci.edu/pub/ietf/html/draft-ietf-html-relrev-00.txt ftp.ics.uci.edu])
* 1996-11-13 [http://www.w3.org/Architecture/NOTE-link Describing and Linking Web Resources]
* 1997-01-23 [http://lists.gnu.org/archive/html/lynx-dev/1997-01/msg00537.html LYNX-DEV Lynx and the LINK tag]
* 1997-01-24 [http://lists.w3.org/Archives/Public/w3c-sgml-wg/1997Jan/0357.html Taxonomy list]
* 1997-03-28 [http://www.w3.org/TR/WD-htmllink-970328 W3C Working Draft: Hypertext Links and Meta Information in HTML]

=== previous attempts at documenting ===
There have been previous attempts at documenting known rel values, most of which fell out of date due to being dependent on a single author maintaining them. They're listed here purely for historical reasons, and are not sufficient to be references of their own (since they're just individual curations of other references)
* [http://fantasai.tripod.com/qref/Appendix/LinkTypes/ltdef.html Link Type Definitions Glossary] by fantasai
* ...

== related ==
{{rel-related-pages}}
* [[elemental-microformats]]
* [[existing-rev-values]]
* [[existing-class-names]]

== copyright ==

{{cc-pd-license}}