existing-rel-values

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 how is 'rel' used. Regarding rev, see: should 'rev' even be used.

This page is also the official rel registry (WHATWG HTML (original link), W3C HTML5). Add new and proposed rel values to the following section:

• 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 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 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 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• Do not add rel values from obsolete/superceded proposals or drafts, instead add them to the table in the "dropped" section.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:
  • HTML 4.01 section 6.12 Link types (HTML4 Link types)
  • Gleaning Resource Descriptions from Dialects of Languages (GRDDL)
• microformats specifications
  • xfn
  • rel-license
  • rel-nofollow

Keyword	Effect on link	Effect on a, area	Brief description (from the relevant specification where possible)	Link to defining specification
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
alternate	external resource	external relation	Designates substitute versions for the document in which the link occurs. When used together with the lang attribute, it implies a translated version of the document. When used together with the media attribute, it implies a version designed for a different medium (or media).	HTML4 Link types
appendix	allowed	allowed	Refers to a document serving as an appendix in a collection of documents.	HTML4 Link types
bookmark	not allowed	allowed	Refers to a bookmark. A bookmark is a link to a key entry point within an extended document. The title attribute may be used, for example, to label the bookmark. Note that several bookmarks may be defined in each document.	HTML4 Link types
chapter	allowed	allowed	Refers to a document serving as a chapter in a collection of documents.	HTML4 Link types
child	external relation	external relation	The referenced person is a child of the person represented by the current document. It may also indicate that the target document is a hierarchical child, or subdocument, of the current document.	XFN, HTML 4.0 Specification
colleague	not allowed	external relation	the referenced person is a colleague of the person represented by the current document	XFN
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
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").	HTML4 Link types
copyright	allowed	allowed	Refers to a copyright statement for the current document.	HTML4 Link types
co-resident	not allowed	external relation	the referenced person lives in the same residence as the person represented by the current document	XFN
co-worker	not allowed	external relation	the referenced person is a co-worker of the person represented by the current document	XFN
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
date	not allowed	external relation	this person considers the referenced person to be a date (i.e. is dating the referenced person)	XFN
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
glossary	allowed	allowed	Refers to a document providing a list of terms and their definitions that pertain to the current document.	HTML4 Link types
help	allowed	allowed	Refers to a document offering help (more information, links to other sources information, etc.)	HTML4 Link types
its-rules	allowed	not allowed	Refers to a document with external ITS rules.	Internationalization Tag Set (ITS) Version 2.0
kin	not allowed	external relation	the referenced person is part of the extended family of the person represented by the current document	XFN
license	allowed	allowed	…indicates that the [referenced document] is a license for the current page.	rel-license
me	external relation	external relation	the referenced document represents the same person as does the current document	XFN
met	not allowed	external relation	this person has met the referenced person	XFN
muse	not allowed	external relation	the referenced person inspires the person represented by the current document	XFN
neighbor	not allowed	external relation	the referenced person lives nearby the person represented by the current document	XFN
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.	HTML4 Link types
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
parent	external relation	external relation	The referenced person is a parent of the person represented by the current document. It may also indicate that the target document is the hierarchical parent, or container, of the current document.	XFN, HTML 4.0 Specification
prev	external relation	external relation	Refers to the previous document in an ordered series of documents. Some user agents also support the synonym "Previous".	HTML4 Link types
previous	external relation	external relation	Synonym of prev	HTML4 Link types
section	allowed	allowed	Refers to a document serving as a section in a collection of documents.	HTML4 Link types
sibling	not allowed	external relation	the referenced person is a sibling of the person represented by the current document	XFN
spouse	not allowed	external relation	the referenced person is a spouse of the person represented by the current document	XFN
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.	HTML4 Link types
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.	HTML4 Link types
subsection	allowed	allowed	Refers to a document serving as a subsection in a collection of documents.	HTML4 Link types
sweetheart	not allowed	external relation	this person considers the referenced person to be their sweetheart	XFN
tag	not allowed	allowed	…indicates that the [referenced document] is an author-designated "tag" (or keyword/subject) for the current page.	rel-tag
toc	allowed	allowed	Synonym of contents (from "Table Of Contents")	HTML4 Link types
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

notes

• rel="alternate" can take further meaning from additional attributes, such as
  • rel="alternate" lang="fr" (French language version of this page)
  • rel="alternate" media="print" (printable version of this page)
  • rel="alternate" media="handheld" (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.

rel value	summary	proposed in	external spec (if any)
pronunciation	…indicates that the destination of the 'link' element is a document providing a pronunciation lexicon for speech-synthesis purposes.	rel-pronunciation
directory	…indicates that the destination of the hyperlink is a directory listing containing an entry for the current page.	rel-directory
enclosure	…indicates that the destination of that hyperlink is intended to be downloaded and cached.	rel-enclosure	RFC4287
home	…indicates that the [referenced document] is the homepage of the site in which the current page appears.	rel-home
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
vcs-*	…indicates that the destination of the hyperlink is the location of a Version Control System repository related to that page.		rel=vcs-*

HTML5 link type extensions

The following values are registered as link type extensions per the requirements in the WHATWG HTML spec and the requirements in the W3C HTML5 spec.

Before you register a new value:

• Please check the Formats table and DO NOT re-register rel values that are already there. Please note that the W3C HTML WG has made a Decision to drop index, up, first and last from the HTML5 spec itself.
• Please check the 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 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 rel keyword. (A spec that merely defines the file format of the link target but does not define the rel 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

Keyword	Effect on link	Effect on a, area	Brief description	Link to specification	Synonyms	Status
about	Hyperlink	Hyperlink	The resource linked to contains information about the current page.	RFC6903	It might combine with rel-me or rel-author in links to an "about" section focused on an author	proposed
amphtml	Hyperlink	Hyperlink	Specify an alternate version of the document written in AMP HTML	AMP HTML documentation	could be combined with rel=alternate	proposed
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).	Apple's Safari Web Content Guide	probably redundant with rel=icon	proposed
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).	Apple's Safari Web Content Guide	probably redundant with rel=icon	proposed
apple-touch-startup-image	External Resource	Not allowed	Specify a splashscreen for Web apps on iOS Safari	Apple's Safari Web Content Guide	maybe redundant with rel=icon with the sizes attribute?	proposed
archived	External Resource	Hyperlink Annotation	The target resource is archived and kept largely or solely for historical purposes.	rel="archived" description		proposed
attachment	Hyperlink	Hyperlink	The resource linked to is "attached" to this document, similar to email attachments. Used in WordPress.	No formal specification		proposed
authorization_endpoint	External Resource	Not allowed	Specify a hosted authorization server	IndieAuth spec		proposed
canonical	Hyperlink	Hyperlink	Specifies the canonical URL for the current document in order to help avoid duplicate content.	Canonical meta tag Canonicalization at Google Webmaster Central Microsoft Webmaster Center Yahoo! Search Blog		proposed
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
code-repository	Hyperlink	Hyperlink	indicates a code repository location. For link, it specifically indicates, in the case of server-generated content, the location of source code responsible for the generation of the current page, or, in the case of static files, where copies of the current page are housed). If the specific data/content built up at the page is stored separately from the generator (e.g., the code for a CMS vs. the specific CMS instance's SQL tables or JSON data files), this only refers to the generator and content-repository should be used to indicate the location for the storage of content. Otherwise, the code repository can be considered as also including the content. While the repository should contain its own license file, the code-license rel-value is proposed as a direct pointer to the license (see also content-license).			proposed
code-license	Hyperlink	Hyperlink	indicates a license for code (a proposed broader replacement for jslicense). For link, it specifically indicates, in the case of server-generated content, the location of the license for all source code responsible for the generation of the current page, or, in the case of static files, the location of the license for all of these files). If the specific data/content built up at the page is stored separately from the generator (e.g., the code for a CMS vs. the specific CMS instance's SQL tables or JSON data files), this only refers to the generator and content-license should be used to indication the license for the content. Otherwise, code-license can be considered as also covering the license of the content. Pointing to the repository containing the static or generator code files should be done with code-repository (and content-repository for any separate content).			proposed
component	External Resource	Not allowed	Specify an HTML document that is treated as a component of this document.	Web Components		proposed
chrome-webstore-item	External Resource	Not allowed	Link tag to declare for app and extensions inline installations hosted in the Chrome Web Store.	Using Inline Installation		proposed
content-repository	Hyperlink	Hyperlink	indicates a repository housing data content. For link, it specifically indicates, in the case of server-generated content, the location where separately housed data files used to populate the current page are stored (otherwise "code-repository" is sufficient to include content as well as code). If the specific data/content built up at the page is stored separately from the generator (e.g., the code for a CMS vs. the specific CMS instance's SQL tables or JSON data files), this only refers to the data/content files and code-repository should be used to indicate the location for the storage of the generator source files. Otherwise, code-repository can be considered as also including the content instead. While the repository should contain its own license file, the content-license rel-value is proposed as a direct pointer to the license (see also code-license).			proposed
content-license	Hyperlink	Hyperlink	indicates a license for data content. For link, it specifically indicates, in the case of server-generated content, the location of the license for all separately housed data files used to populate the current page are stored, (otherwise "code-license" is sufficient to cover the license of content as well as code)). If the specific data/content built up at the page is stored separately from the generator (e.g., the code for a CMS vs. the specific CMS instance's SQL tables or JSON data files), this only refers to the data/content files and code-license should be used to indication the license for the generator source files. Otherwise, code-license can be considered as also covering the license of the content. Pointing to the repository containing the data files should be done with content-repository (and code-repository for the static or generator code files).			proposed
DCTERMS.conformsTo	External Resource	Not allowed	An established standard to which the described resource conforms. Requires Dublin Core namespace declaration: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms	It may be replaced by the literal value in form of <meta name="DCTERMS.conformsTo" content="..." />	proposed
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: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms	It may be replaced by the literal value in form of <meta name="DCTERMS.contributor" content="..." />	proposed
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: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms	It may be replaced by the literal value in form of <meta name="DCTERMS.creator" content="..." />	proposed
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: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms	It may be replaced by the literal value in form of <meta name="DCTERMS.description" content="..." />	proposed
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: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms		proposed
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: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms		proposed
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: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms		proposed
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: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms		proposed
DCTERMS.isPartOf	External Resource	Not allowed	A related resource in which the described resource is physically or logically included. Requires Dublin Core namespace declaration: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms		proposed
DCTERMS.isReferencedBy	External Resource	Not allowed	A related resource that references, cites, or otherwise points to the described resource. Requires Dublin Core namespace declaration: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms		proposed
DCTERMS.isReplacedBy	External Resource	Not allowed	A related resource that supplants, displaces, or supersedes the described resource. Requires Dublin Core namespace declaration: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms		proposed
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: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms		proposed
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: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms		proposed
DCTERMS.license	External Resource	Not allowed	A legal document giving official permission to do something with the resource. Requires Dublin Core namespace declaration: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms	It may be replaced by the literal value in form of <meta name="DCTERMS.license" content="..." />	proposed
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: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms	It may be replaced by the literal value in form of <meta name="DCTERMS.mediator" content="..." />	proposed
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: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms	It may be replaced by the literal value in form of <meta name="DCTERMS.publisher" content="..." />	proposed
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: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms		proposed
DCTERMS.relation	External Resource	Not allowed	A related resource. Requires Dublin Core namespace declaration: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms		proposed
DCTERMS.replaces	External Resource	Not allowed	A related resource that is supplanted, displaced, or superseded by the described resource. Requires Dublin Core namespace declaration: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms		proposed
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: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms		proposed
DCTERMS.rightsHolder	External Resource	Not allowed	A person or organization owning or managing rights over the resource. Requires Dublin Core namespace declaration: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms	It may be replaced by the literal value in form of <meta name="DCTERMS.rightsHolder" content="..." />	proposed
DCTERMS.source	External Resource	Not allowed	A related resource from which the described resource is derived. Requires Dublin Core namespace declaration: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms		proposed
DCTERMS.subject	External Resource	Not allowed	The topic of the resource. Requires Dublin Core namespace declaration: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/" />	DCMI Metadata Terms		proposed
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.	The 'disclosure' Link Relation Type		proposed
discussion	Hyperlink	Hyperlink	Refers to discussion of the current document or post.	rel-discussion		proposed
donation	Hyperlink	Hyperlink	Indicates that the destination of the hyperlink provides a way to show or give support (e.g. financial) for the current page on a voluntary basis	No formal specification	Closely related to rel-payment	proposed
dns-prefetch	External Resource	Not allowed	Tells the browser to perform dns lookup for host names ahead of use.	Mozilla documentation Google documentation		proposed
edit	Hyperlink	Not allowed	Tells the browser where the current page can be edited	Universal Edit Button Alternate Linking Scheme. Implemented in at least MediaWiki.		proposed
EditURI	External Resource	Not allowed	A blogging auto discovery value, commonly used by WordPress	AtomAPI		proposed
enclosure	External Resource	External Resource	Indicates that the referred resource is intended to be downloaded and cached.	rel-enclosure		proposed
entry-content	Not allowed	External Resource	Indicates that the referenced document is an alternative display source for an Internet Explorer Web Slice.	Web Slice format specification 0.9		proposed
external	Not allowed	Hyperlink	Indicates that the referenced document is not part of the same site as the current document.	rel-external		proposed
first	Hyperlink	Hyperlink	Indicates that the document is part of a sequence, and that the link is leading to the document that is the first logical document in the sequence.	W3C Working Draft 13 January 2011		proposed
gbfs	External Resource	Not allowed	The location of the gbfs auto-discovery file	General Bikeshare Feed Specification		proposed
gtfs-static	External Resource	Not allowed	Indicates the associated GTFS Static file	General Transit Feed Specification Reference		proposed
gtfs-realtime	External Resource	Not allowed	Indicates the associated GTFS-Realtime file	GTFS-realtime Reference		proposed
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	rel-root	proposed
hub	Hyperlink	Hyperlink	Refers to a hub that enables registration for notification of updates to the current page.	PubSubHubbub Spec WebSub spec		proposed
import	External Resource	Not allowed	HTML Imports are a way to include and reuse HTML documents in other HTML documents.	HTML Imports		proposed
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
root	Hyperlink	Hyperlink	The target document is the root node of the hierarchical tree structure that hosts the current document	No formal specification	rel-home	proposed
index	Hyperlink	Hyperlink	Refers to a document providing a list of topics with pointers that pertain to the current document.	HTML4		proposed
issues	Hyperlink	Hyperlink	Refers to issues regarding the current document or specification.	rel-discussion		proposed
jslicense	Hyperlink	Hyperlink	Refers to a document with JavaScript source code and license information (also called a 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.	rel-jslicense		proposed
last	Hyperlink	Hyperlink	Indicates that the document is part of a sequence, and that the link is leading to the document that is the last logical document in the sequence.	W3C Working Draft 13 January 2011		proposed
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 <a rel="lightbox[group]"><img src="http:example.com/img.jpg"></a>	Lightbox 2 (needs actual specification to be kept in this list, this link is just documentation of one implementation)		proposed
lightvideo	Not allowed	Video Pop-Up	Loads the video in a lightbox effect	Lightbox2 - How to display video content		proposed
main	Hyperlink	Hyperlink	The current page is a subsection or a less important page than the target resource	No formal specification	It can be a synonym of rel-parent when the latter refers to a document and not a person. It differs however from rel-home and rel-root, as the latter refer only to the topmost resource in the hierarchical tree structure (and in this case they may be combined with main). Note that rel-main does not necessarily refer to a higher node in a tree structure, as the target resource can simply be a more important sibling node.	proposed
manifest	External Resource	Not allowed	Imports or links to a manifest	W3C Manifest for web application		proposed
mask-icon	External Resource	Not allowed	Specify a Webpage Icon for a “Pinned Tabs” on Safari 9.	probably redundant with rel-icon		proposed
meta	External Resource	Not allowed	External metadata about the HTML document	W3C's RDF/XML Syntax Specification		proposed
micropub	External Resource	Not allowed	the micropub endpoint for creating new posts	Micropub scecification		proposed
noopener	Not allowed	Annotation	Requires that any browsing context created by following the hyperlink must not have an opener browsing context.	4.6.6.11 Link type ”noopener"		proposed
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.	OpenID Authentication 1.1		proposed
openid.server	External Resource	Not allowed	The OpenID server for the relying party to contact for OpenID 1.1 authentication	OpenID Authentication 1.1		proposed
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.	OpenID Authentication 2.0		proposed
openid2.provider	External Resource	Not allowed	The OpenID server for the relying party to contact for OpenID 2.0 authentication	OpenID Authentication 2.0		proposed
p3pv1	External Resource	Not allowed	References a machine-readable privacy policy description in the P3P format	P3P spec		proposed
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.	PGP-Signed Comments		proposed
pingback	External Resource	Not allowed	gives the address of the pingback server that handles pingbacks to the current document	Pingback		proposed
preconnect	External Resource	Not allowed	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.	Resource Hints Working Draft		proposed
prerender	External Resource	External Resource	Prerenders the Web page targeted by the link including running it scripts.	rel-prerender		proposed
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.	rel-profile		proposed
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.	Google help page		proposed
radioepg	External Resource	External Resource	Indicates that the referenced document is a RadioDNS Service Information document (ETSI TS 102 818 s10.2.3) containing information on the radio station that publishes the current page	RadioDNS Documentation		proposed
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.	HTML rel rendition		proposed
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.	RFC2822 (originally RFC822)		ratified
schema.DCTERMS	External Resource	Not allowed	Maps the prefix "DCTERMS" for use in other Dublin-Core related link relations (such as DCTERMS.creator) and meta keywords	Section 4.2 of "Expressing Dublin Core metadata using HTML/XHTML meta and link elements"	see also "WhatWG MetaExtensions Wiki for usage examples in meta keywords	proposed
service	External Resource	Not allowed	Atom Publishing Protocol editing service autodiscovery.	Documentation on the WHATWG wiki		proposed
shortlink	External Resource	Not allowed	Specifies the preferred shortened URL for the page.	shortlink spec		proposed
sidebar	Hyperlink	Hyperlink	Indicates that the referenced document is intended to be shown in a secondary browsing context.	rel-sidebar		proposed
sitemap	External Resource	Not allowed	Provides a link to an XML document describing the layout of the site.	rel-sitemap		proposed
subresource	External Resource	Not allowed	An external resource intended for use within the current page.	Chromium documentation		proposed
sword	Hyperlink	Not allowed	SWORD is a lightweight protocol for remotely depositing content into repositories. .The SWORD project	rel-sword		proposed
syndication	Hyperlink	Hyperlink	Refers to a page which is a syndicated copy of the current page.	rel-syndication		proposed
timesheet	External Resource	Not allowed	Applies a timesheet to the document.	non-normative section in the Timesheet spec		proposed
token_endpoint	External Resource	Not allowed	Specify an HTTP endpoint that Micropub clients can use to obtain an access token given an authorization code	IndieAuth spec		proposed
webmention	External Resource	Hyperlink	gives the address of the webmention endpoint that handles webmentions to the current document	Webmention specification		proposed
widget	External Resource	External Resource	Autodiscovery for W3C widgets	non-normative section in the Widget packaging spec		proposed
wlwmanifest	External Resource	Not allowed	Windows Live Writer manifest autodiscovery	documentation on MSDN		proposed
image_src	External Resource	Not allowed	Specify a Webpage Icon for use by Facebook, Yahoo, Digg, etc.	Unknown, but see for instance this	probably redundant with rel=icon	proposed
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	CMIS 1.0, Section 3.4.3.4		proposed
stylesheet/less	External Resource	Not allowed	Less CSS framework stylesheets.	Less CSS usage		proposed
yandex-tableau-widget	External Resource	Not allowed	Lets webmasters configure the appearance of their own site widgets in Yandex.Browser	Yandex's Tableau API		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.

rel value	summary	brainstormed in and usage in the wild
accessibility	indicate[s] that the destination of that hyperlink contains accessibility information for the current page.	blog post which itself uses the rel value in a <link> tag in the head of the document.
author	indicate[s] that the destination of that hyperlink represents the author of the current page. Combines with rel-me to chain authorship information.	Google has said it will index rel-Author in this blog post, with further discussion of the rel-me connection See also the HTML5 spec
bibliography	indicate[s] that the destination of that hyperlink is a bibliography for the current page.	mailing list post, 2007-10-15
cite	indicate[s] that the destination of that hyperlink is an authoritative source or a precedent to the current page.	distributed-conversation-brainstorming
embed	destination of the link is an version of the current page suitable for embedding in other pages	IndieWeb rel-embed examples and brainstorming
group	the referenced document represents a group to which the person represented by the current document belongs	group-brainstorming
longdesc	Alternative to the img longdesc attribute, for use on visible links	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.
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 TobyInk by email)
member	the referenced document represents a member of the group represented by the current document	group-brainstorming
m_PageScroll2id	JS to scroll to a defined ID	group-brainstorming
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.	resource hints draft
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.	resource hints draft
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.	resource hints draft
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
shortlink	the referenced document represents the current document but with a shorter URL	blog post
source	the referenced document represents the source code for the current document or project	source-brainstorming blog post
vcalendar-parent	link from an event to a containing event	hCalendar 1.1 draft
vcalendar-child	link from an event to a contained event	hCalendar 1.1 draft
vcalendar-sibling	link from an event to a related event with the same container	hCalendar 1.1 draft
status	the referenced document represents the status (or source of status updates) for the author of this document	blog post
https://api.w.org/	Link to Wordpress API	Official Wordpress theme

more brainstorming

See also:

• genealogy-brainstorming for some thoughts on possible additional values for family relationships (use existing XFN parent, child, sibling, spouse, kin values first though)
• xpn-brainstorming for some thoughts on possible additional values for professional relationships (use existing XFN co-worker, 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:

• Meta Information in DevMo Docs (DevMo)
• Microsummary
• Web Communication Link Relationships (WCLR)
• W3C Link Relationship values draft (LRdraft) - from a draft of the HTML spec circa 1991.
• HTML5 draft Liable to change
• FOAF Project Wiki: Autodiscovery (FOAF)
• RFC4685
• Google Blog

rel value	summary	origin	proposal(s)
archive	index of archived entries	unknown, perhaps Wordpress open source blogging software	WCLR
archives	Provides a link to a collection of records, documents, or other materials of historical interest.		HTML5
author	see brainstorming above for suggested use by google	unknown	DevMo / HTML5
canonical	To help search engines disambiguate the same page with multiple representations	Google	Google/Microsoft/Yahoo!, Ask Jeeves
comment	…	…	WCLR
contribution	…	…	WCLR
EditURI	Location of the xml-rpc gateway for a Wordpress install that allows external programs to add, edit and delete posts. Used by "WordPress blog client" software for automating posting and updating blog content from your desktop.	Seen in WordPress, e.g. [1].	Description stubbed in rel-edituri.
endorsed	…	…	WCLR
fan	xxxx.	…	hcard-user-profile-authoring
feed	Gives the address of a syndication feed for the current document.	…	WCLR/ HTML5
footnote	Location of the footnote on a link to a footnote.	Markdown preprocessors such as Maruku	HTML5
icon	Imports an icon to represent the current document. (Allowed in link only)	HTML5	WCLR/HTML5
kinetic-stylesheet	Imports a KSS 'kinetic stylesheet' to bind dynamic behavior to elements	Used in the Plone Content Management System	…
lightbox	Hook - Indicates that following the link will trigger a "lightbox" script (Allowed in link only)	(Google search for rel=lightbox in the wild) Use "lightbox" instead of "clearbox" or "prettyPhoto"	…
made	…	…	LRdraft
meta	…	1999 W3C RDF syntax REC	FOAF
microsummary	…	…	Microsummary, be aware of: microsummary issues
noreferrer	indicates that no referrer information is to be leaked when following the link.	HTML5	HTML5
openid.delegate	…	(Google search for rel=openid.* in the wild)	…
openid.server	…	(Google search for rel=openid.* in the wild)	…
permalink	indicate a permanent link for some, or all, content within the document. obsolete; use bookmark instead.	…	WCLR
pgpkey	(see also rel-publickey)	…	[2], [3]
pingback	Gives the address of the pingback server that handles pingbacks to the current document. (Allowed in link only)	…	WCLR/ HTML5
popover	Used by a JS widget to display a large, descriptive tooltip.	Twitter's Bootstrap Popover.js	…
prefetch	Specifies that the target resource should be pre-emptively cached. (Allowed in link only)	…	HTML5
privacy	Specifies that the target resource is the privacy policy.	…	…
publickey	(see also rel-pgpkey)	…	[4]
referral	…	…	WCLR
related	…	…	WCLR
replies	indicates a continued thread	unknown	RFC4685
respond-proxy	Working with respond.js - proxy on external server	[5]	[6]
respond-redirect	Working with respond.js - redirect location on local server	[7]	[8]
resource	…	…	WCLR
search	…	unknown	unknown
sitemap	Links to a site map document.	…	http://www.sitemaps.org/
sponsor	…	…	WCLR
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.	Twitter's Bootstrap Tooltip.js (and likely other JS tools)	…
trackback	…	unknown, perhaps open source Movable Type blogging software	WCLR
unendorsed	(probably redundant to nofollow)	…	WCLR
user	…	…	WCLR
wlwmanifest	Used by "Windows Live Writer," a Microsoft blog client for automating posting and updating blog content from your desktop.	Seen in WordPress, e.g. [9]. 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:

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

These are covered by HTML5 already:

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

The rest now seem unnecessary.

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.

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	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" [10]	Dublin Core

Issues need updating given new information from linked resources.

Notes:

• Dublin Core. This search may help: [11].
  • examples from that search only use invisible <link href> element. At first glance it appears the results from the search show only uses 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.
    • RFC2731 defines rel="schema.AC" and rel="schema.RC" with the pattern rel="schema.PREFIX" 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 <link href> appears to be more appropriate than <a href> 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: <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"> (for the namespace declaration, followed by) <meta name="DCTERMS.[element]" content="[element.value]"> for related elements.
      • Note: schema.DCTERMS is conventionally related to an upgraded elements list than 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 <a href> appears to be strictly theoretical. See 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 ([12]), 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 "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 here.
• "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 <link rel="schema.DCTERMS" href="http://purl.org/dc/terms/"> for namespace declarations.

• According to DCMI specification linked above, as well as "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 "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 <link> 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)

Link: <http://creativecommons.org/publicdomain/zero/1.0/>; rel="license"

For multiple licenses (e.g. CC-SA and GPL), simply use multiple Link: headers.

Link: <http://creativecommons.org/licenses/by-sa/3.0/>; rel="license"
Link: <http://www.gnu.org/licenses/gpl.html>; rel="license"

Example: similarly, linking to a copyright statement for an image:

Link: <http://example.org/copyright.html>; rel="copyright"

or providing a brief inline copyright statement:

Link: <data:text/plain;charset=utf-8,Copyright 2013 ExampleCo, All Rights Reserved.>; rel="copyright"

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 Maze+XML
• See Collection+JSON
• See OpenSearch
• See The Create-Form and Edit-Form Link Relations (RFC6861)
• See Workflow-Related Link Relations at Messages.io

rel value	summary (from the relevant specification where possible))	defining specification
self	From http://www.ietf.org/rfc/rfc4287.txt : The value "self" signifies that the IRI in the value of the href attribute identifies a resource equivalent to the containing element.	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
compensatingtx	Link to a resource representing information about a compensating transaction for each member transaction of a Long-Lived Compensating Transaction	See Compensating Transaction Link Relation
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
events	Link to a collection resource representing a list of subscribe-able events.	See Events Link Relation
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
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 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 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 Collection Document Media Type Specification
sub	When included in a resource representation of an event, the "sub" (subscription) link relation MAY identify a target resource that represents the ability to subscribe to the pub/sub event-type resource in the link context.	See Subscription Link Relation
unsub	When included in a resource representation of an event, the "unsub" (subscription cancellation) link relation MAY identify a target resource that represents the ability to un-subscribe from the pub/sub event-type resource in the link context.	See Subscription Cancellation Link Relation
version-history	When included on a versioned resource, this link points to a resource containing the version history for this resource.	RFC 5829
latest-version	When included on a versioned resource, this link points to a resource containing the latest (e.g., current) version.	RFC 5829
working-copy	When included on a versioned resource, this link points to a working copy for this resource.	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.	RFC 5829
predecessor-version	When included on a versioned resource, this link points to a resource containing the predecessor version in the version history.	RFC 5829
successor-version	When included on a versioned resource, this link points to a resource containing the successor version in the version history.	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:

• HTML3 (HTML3) / has been superceded by HTML 3.2 - which itself has been superceded by HTML 4.0 - which itself has been updated by HTML 4.01, commonly referred to as "HTML 4" in this wiki and other places.)
• 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.

rel value	summary	defining specification	why dropped
banner	Was used to reference another document to be used as banner for this document (i.e. a form of "include" statement).	HTML3	unknown
begin	identifies the author-defined start of a sequence of documents of which the current document is a node.	HTML4dropped	unknown
biblioentry	identifies a bibliographic entry	HTML4dropped	unknown
bibliography	identifies a bibliography	HTML4dropped	unknown
child (obsolete/superceded)	the target document is a hierarchical child, or subdocument, of the current document	HTML4dropped	unknown
citation	the target is a bibliographic citation	HTML4dropped	unknown
collection	the target document is an collection that contains the current document	HTML4dropped	unknown
definition	identifies a definition of a term	HTML4dropped	unknown
disclaimer	identifies a hypertext link to a legal disclaimer	HTML4dropped	unknown
editor	identifies a hypertext link to an editor	HTML4dropped	unknown
end	identifies the author-defined end of a sequence of documents of which the current document is a node.	HTML4dropped	unknown
footnote	the anchor is a footnote marker and the target is a footnote	HTML4dropped	unknown
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
origin	synonym for top	HTML4dropped	unknown
parent (obsolete/superceded)	the target document is the hierarchical parent, or container, of the current document	HTML4dropped	unknown
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
publisher	identifies a hypertext link to a publisher	HTML4dropped	unknown
sibling (obsolete/superceded)	the target document is a child of a common parent, or a hierarchical peer of the current document	HTML4dropped	unknown
top	the target document is the logical top node of the tree (see also begin)	HTML4dropped	unknown
trademark	identifies a hypertext link to a trademark notice	HTML4dropped	unknown
translation	the target is a translation to another language	HTML4dropped	unknown
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 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 explicitly dropped from HTML5. Per: Issue 118 Decision (emphasis added):

  "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."

rel value	summary	defining specification	why dropped
first	Synonym for start	HTML4dropped - never in an official spec	Explicitly dropped from HTML5 interim draft yet permitted for external registry
index	Refers to a document providing an index for the current document.	was in HTML4; the token has been re-registered within the HTML5 link type extensions and is now valid.	Explicitly dropped from HTML5 interim draft yet permitted for external registry
last	Refers to the last document in a collection of documents.	HTML4dropped - never in an official spec	Explicitly dropped from HTML5 interim draft yet permitted for external registry
up	When the document forms part of a hierarchy, this link references the immediate parent of the current document. Synonym for parent.	was in HTML3 - but dropped in HTML4	Explicitly dropped from HTML5 interim draft yet permitted for external registry

See related 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.

rel value	origin / proposal	why rejected
logo	Relogo.org	rejected-formats#Logo
pavatar	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 Hypertext links in HTML (copies: ftp.ics.uci.edu)
• 1996-11-13 Describing and Linking Web Resources
• 1997-01-23 LYNX-DEV Lynx and the LINK tag
• 1997-01-24 Taxonomy list
• 1997-03-28 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)

• Link Type Definitions Glossary by fantasai
• ...

related

• rel
• existing rel values
• rel examples
• rel FAQ
• rel design pattern
• rel values issues
• rel-registry
• elemental-microformats
• existing-rev-values
• existing-class-names

copyright

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