microformats2

<entry-title>microformats 2.0</entry-title>

Welcome to the in-progress development of microformats 2.0.

Summary

Microformats 2.0 improves ease of use and implementation for both authors (publishers) and developers (parser implementers), with the following simplifications:

1. which class names are used for microformats (those that start with 'h-' 'p-' 'u-' 'dt-', 'e-')
2. flat sets of properties for all microformats (hierarchical data uses nested microformats) which are all optional and plural (applications needing a singular semantic may use first instance)
3. syntax independent vocabularies - the previous two simplifications enable generic parsing (thus automatic JSON/XML/RDF output) and syntax independent development of vocabularies
4. simpler markup for common use-cases - common microformats use-cases have been simplified even further with generic parsing rules and a few implied generic properties: name, url, photo.

simple microformats 2 examples

Here are a few simple microformats 2.0 examples the demonstrate a most of the changes (Parsed JSON examples are a draft experiment - feedback invited!)

Simple person reference:

<span class="h-card">Frances Berriman</span>

Parsed JSON:

[{ 
  "type": ["h-card"],
  "properties": {
    "name": ["Frances Berriman"] 
  }
}]

---

Simple hyperlinked person reference

<a class="h-card" href="http://benward.me">Ben Ward</a>

Parsed JSON:

[{ 
  "type": ["h-card"],
  "properties": {
    "name": ["Ben Ward"],
    "url": ["http://benward.me"]
  }
}]

---

Simple hyperlinked person image

<a class="h-card" href="http://rohit.khare.org/">
 <img alt="Rohit Khare"
      src="https://s3.amazonaws.com/twitter_production/profile_images/53307499/180px-Rohit-sq_bigger.jpg" />
</a>

Parsed JSON:

[{ 
  "type": ["h-card"],
  "properties": {
    "name": ["Rohit Khare"],
    "url": ["http://rohit.khare.org"],
    "photo": ["https://s3.amazonaws.com/twitter_production/profile_images/53307499/180px-Rohit-sq_bigger.jpg"]
  }
}]

More details of how simple cases work in microformats-2-implied-properties.

Notes:

1. "type" uses the full microformat root class name for consistent identification.
2. all properties are optional and syntactically plural with parsed values provided in document order; particular microformats (and applications there-of) may apply specific/singular semantics to first value of a property.
3. properties could be explicitly bound as URIs using the html5-profile attribute proposal, or perhaps a 'vocab' attribute instead (more intuitive than the overloaded 'profile').

v2 vocabularies

Status: draft. Please review and provide feedback in IRC.

h-adr

profile/itemtype: http://microformats.org/profile/h-adr

properties:

• p-post-office-box
• p-extended-address
• p-street-address
• p-locality
• p-region
• p-postal-code
• p-country-name
• p-label - new in vCard4 (RFC6350)
• p-geo (or u-geo with a RFC 5870 geo: URL) - new in vCard4 (RFC6350)
• p-latitude - new in vCard4 (RFC6350 from RFC 5870)
• p-longitude - new in vCard4 (RFC6350 from RFC 5870)
• p-altitude - new in vCard4 (RFC6350 from RFC 5870)

For backward compatibility, microformats 2 parsers SHOULD detect the following root class name and property names. A microformats 2 parser may use existing microformats parsers to extract these properties. If an "h-adr" is found, don't look for an "adr" on the same element. compat root class name:

• adr

properties: (parsed as p- plain text unless otherwise specified)

• post-office-box
• extended-address
• street-address
• locality
• region
• postal-code
• country-name

h-card

profile/itemtype: http://microformats.org/profile/h-card

properties:

• p-name
• p-honorific-prefix
• p-given-name
• p-additional-name
• p-family-name
• p-honorific-suffix
• p-nickname
• u-email
• u-logo
• u-photo
• u-url
• p-category
• p-adr
• p-post-office-box
• p-extended-address
• p-street-address
• p-locality
• p-region
• p-postal-code
• p-country-name
• p-label
• p-geo or u-geo with a RFC 5870 geo: URL, new in vCard4 (RFC6350)
• p-latitude
• p-longitude
• p-altitude - new in vCard4 (RFC6350 from RFC 5870)
• p-tel
• p-note
• dt-bday
• u-key
• p-org
• p-organization-name
• p-organization-unit
• u-impp per RFC 4770, new in vCard4 (RFC6350)
• p-sex new in vCard4 (RFC6350)
• p-gender-identity new in vCard4 (RFC6350)
• dt-anniversary new in vCard4 (RFC6350)
• ...

For backward compatibility, microformats 2 parsers SHOULD detect the following root class name and property names. A microformats 2 parser may use existing microformats parsers to extract these properties. If an "h-card" is found, don't look for a "vcard" on the same element. compat root class name:

• vcard

properties: (parsed as p- plain text unless otherwise specified)

• fn - parse as p-name
• honorific-prefix
• given-name
• additional-name
• family-name
• honorific-suffix
• nickname
• email - parse as u-
• logo - parse as u-
• photo - parse as u-
• url - parse as u-
• category
• adr - parse as p-adr h-adr including compat root adr
• extended-address
• street-address
• locality
• region
• postal-code
• country-name
• label
• geo - parse as p-geo h-geo including compat root geo
• latitude
• longitude
• tel
• note
• bday - parse as dt-
• key - parse as u-
• org
• organization-name
• organization-unit
• ...

Note: use of 'value' within 'tel' should be automatically handled by the support of the value-class-pattern. And for now, the 'type' subproperty of 'tel' is dropped/ignored. If there is demonstrable documented need for additional tel types (e.g. fax), we can introduce new flat properties as needed (e.g. p-tel-fax).

h-entry

profile/itemtype: http://microformats.org/profile/h-entry

properties:

• p-name
• p-entry-summary
• e-entry-content
• dt-published
• dt-updated
• p-author
• p-category
• u-url
• u-uid
• p-geo
• p-latitude
• p-longitude

For backward compatibility, microformats 2 parsers SHOULD detect the following root class name and property names. A microformats 2 parser may use existing microformats parsers to extract these properties. If an "h-entry" is found, don't look for a "hentry" on the same element. compat root class name:

• hentry

properties: (parsed as p- plain text unless otherwise specified)

• entry-title - parse as p-name
• entry-summary
• entry-content
• published - parse as dt-
• updated - parse as dt-
• author
• category
• geo - parse as p-geo h-geo including compat root geo
• latitude
• longitude
• ...

h-event

profile/itemtype: http://microformats.org/profile/h-event

properties:

• p-name
• dt-start
• dt-end
• p-description
• u-url
• p-category
• p-location
• p-geo
• p-latitude
• p-longitude
• ...

For backward compatibility, microformats 2 parsers SHOULD detect the following root class name and property names. A microformats 2 parser may use existing microformats parsers to extract these properties. If an "h-event" is found, don't look for a "vevent" on the same element. compat root class name:

• vevent

properties: (parsed as p- plain text unless otherwise specified)

• summary - parse as p-name
• dtstart - parse as dt-start
• dtend - parse as dt-end
• description
• url - parse as u-
• category
• location
• geo - parse as p-geo h-geo including compat root geo
• latitude
• longitude
• ...

h-geo

profile/itemtype: http://microformats.org/profile/h-geo

properties:

• p-latitude
• p-longitude
• p-altitude - new in vCard4 (RFC6350 from RFC 5870)

For backward compatibility, microformats 2 parsers SHOULD detect the following root class name and property names. A microformats 2 parser may use existing microformats parsers to extract these properties. If an "h-geo" is found, don't look for an "geo" on the same element. compat root class name:

• geo

properties: (parsed as p- plain text unless otherwise specified)

• latitude
• longitude

v2 vocab notes

Notes:

• All v2 vocabularies are defined as flat lists of properties of an object/item, and thus can be used in microformats-2 syntax as shown, or in microdata items, or RDFa. The microformats-2 property parsing prefixes "p-", "u-", "dt-", "e-" are omitted when using defined properties in microdata itemprop and RDFa property as those syntaxes have their own element-specific parsing rules.
• Profile URLs are provided for use with the HTML4 profile attribute, microdata itemtype, and RDFa vocab/typeof attributes (though the latter requires slicing off the trailing segment of the profile for the typeof attribute, and leaving the rest in vocab).

v2 vocab to-do

To do:

• actual profile documents at http://microformats.org/profile/h-* URLs mentioned above.
• Provide any necessary microdata-specific language as needed (e.g. to be comparably understandable to the sample vCard4/hCard1 microdata vocabulary. Also provide any necessary RDFa-specific language as needed. Both preferably in a generic vocabulary-independent way.

combining microformats

Since microformats 2 uses simple flat sets of properties for each microformat, multiple microformats are combined to indicate additional structure.

h-event location h-card

Events commonly have venue information with additional structure, like address information. For example:

<div class="h-event">
  <a class="p-name u-url" href="http://indiewebcamp.com/2012">
    IndieWebCamp 2012
  </a>
  from <time class="dt-start">2012-06-30</time> 
  to <time class="dt-end">2012-07-01</time> at 
  <span class="p-location h-card">
    <a class="p-name u-url" href="http://urbanairship.com/">
      Urban Airship
    </a>, 
    <span class="p-street-address">334 NW 11th Ave.</span>, 
    <span class="p-locality">Portland</span>, 
    <abbr class="p-region" title="Oregon">OR</abbr>
  </span>
</div>

The nested h-card used to structure the p-location of the h-event is represented as a structured value for "location" in the JSON, which has an additional key, "value" that represents the plain text version parsed from the p-location.

Parsed JSON:

[{ 
  "type": ["h-event"],
  "properties": {
    "name": ["IndieWebCamp 2012"],
    "url": ["http://indiewebcamp.com/2012"],
    "start": ["2012-06-30"],
    "end": ["2012-07-01"],
    "location": [{
      "value": "Urban Airship, 334 NW 11th Ave., Portland, OR",
      "type": ["h-card"],
      "properties": {
        "name": ["Urban Airship"],
        "url": ["http://urbanairship.com/"],
        "street-address": ["334 NW 11th Ave."],
        "locality": ["Portland"],
        "region": ["Oregon"]
      }
    }]
  }
}]

Notes:

• The 'location' value reflects the visible text of its element, including spaces and punctuation, as well as the state abbreviation 'OR'. The 'h-card' property values are only what is marked up, and thus include structure values without extra punctuation, and the state takes the expanded form from the title attribute of its <abbr> element.

Examples in the wild

Please add new examples in the wild of microformats-2 to the top of this list. When it gets too big we can move it to a separate page like microformats-2-examples-in-wild.

• ...
• WebFWD by Mozilla has microformats-2 h-card markup on experts and team pages
• IndieWebCamp has microformats-2 h-event markup with nested h-cards for the organizers and the location.
• Mozilla Events page has microformats-2 h-event markup with attendees marked up with h-card.

About This Brainstorm

The rest of this page is a brainstorm currently written in narrative / exploratory format, that is, acknowledging the success that microformats have had, why so, and then a walk through of known issues with microformats in general along with iteration of ways to address said issues, ending up with the current microformats 2.0 design as a conclusion.

The proposals build on each other resulting in a solution that addresses the vast majority of general issues. The proposed changes merit a major version number increment, hence microformats 2.0.

This mathematical proof/derivation style is used to explicitly encourage understanding (and double-checking) of the rational steps taken in the development of microformats 2.0. Reasons are documented, sometimes along with alternatives considered (and reasons for rejection of those alternatives).

When the microformats 2.0 brainstorm has evolved sufficiently to demonstrate some degree of stability, usability, and implementability, it will be rewritten in a more declarative specification style, and this narrative/derivation will be archived to a background development page for historical purposes.

— Tantek

Background

2004: In early February microformats were introduced as a concept at eTech, and in September hCard and hCalendar were proposed at FOO Camp.

2010:

• 34% of webdevs use microformats (2010 State of Web Development survey)
• 1.88 billion hCards (per Yahoo SearchMonkey)
• 36 million hCalendar events (ibid)

• XFN -> Social Graph API -> Web as Social Network / Address Book

Addressing Issues

AUTHORS and PUBLISHING

Authors and publishers are perhaps the most important constituency in the microformats community. There are more of them than there are developers, programmers, parsers, etc. and they're the ones that solved the chicken-egg problem by publishing microformats even before tools were available for consuming them.

Therefore we must first address author/publisher general issues with microformats.

can we make the simplest case simpler

Issue: How can we make it easier for authors to publish microformats?

Currently the simplest hCard:

<span class="vcard">
  <span class="fn">
    Chris Messina
  </span>
</span>

requires 2 elements (nested, with perhaps at least one being pre-existing), and 2 class names.

Web authors/designers are used to the simplicity of most HTML tags, e.g. to mark up a heading:

<h1>Chris Messina</h1>

requires just 1 element.

Jeffrey Zeldman pointed out this apparent perceived incremental complexity (2 elements vs 1) during a microformats workshop in 2009 in New York City.

How can we make microformats just as easy?

Proposal: allow root class name only.

This would enable:

<h1 class="vcard">Chris Messina</h1>

requiring only 1 class name for the simplest case.

renaming for usability

Otherwise known as, choosing one form of consistency over another.

Can we do even better?

One of the most common questions asked about hCard is:

Why does hCard use vcard as the root class name?

This slight inconsistency between the name of the format and the name of the root class name consistently causes confusion in a large percentage of newcomers to microformats.

• See issues#hcard-vs-vcard-name for details/links.

Though in microformats we believe very strongly in the principle of reuse, we have to admit that in this case experience/evidence has shown that this may be a case where we re-used something too far beyond it's original meaning. Thus:

Proposal: use root class name "hcard" instead of "vcard" for future hCards.

This would result in:

<h1 class="hcard">Chris Messina</h1>

making the simple case even simpler:

Just 1 additional class name, named the same as the format you're adding. Think hCard, markup class="hcard".

At a minimum for compatibility we should document that parsers should accept "hcard" as an alternative to "vcard" as the root class name for hCard 1.0, and similarly for hCalendar 1.0: "hcalendar" in addition to "vcalendar", "hevent" in addition to "vevent".

However, for microformats-2 we are going to distinguish root class names further by using an "h-" prefix (e.g. "h-card"). Read on to understand why.

simplifying to only needing one element

It's very important for the simple case to be as simple as possible, to enable the maximum number of people to get started with minimum effort. (The idea of using a single class name for a microformat was proposed by Ryan Cannon in 2006 specifically for hCard, and rediscovered by Tantek in 2010 and subsequently generalized to all microformats.)

From there on, it's ok to require incremental effort for incremental return.

E.g. to add any additional information about a person, add explicit property names.

How does this simple root-only case work?

• root class name reflects name of the microformat
• every microformat must require at most 1 property (preferably 0)
  • admit that requiring a field in an application just results in noise (the 90210 problem - apps which require zip code get lots of false 90210 entries), and specify that any application use cases which appear to "require" specific properties must instead define how to imply sensible defaults for them.
• when only a root class name is specified, imply the entire text contents of the element as the value of the primary property of the microformat. e.g.
  • "hcard" implies "fn"
  • hcalendar event - "hevent" - implies "summary"
  • "hreview" implies "summary"
  • "hentry" implies "entry-summary" (perhaps collapse into "summary" - in practice they're not sufficiently semantically distinct to require separate property names)
  • OR instead of making the one implied property be vocabulary specific, introduce a new generic (applicable to all vocabularies) 'p-name' property (subsuming hCard's 'fn'). See microformats 2 brainstorming: further simplifications for latest thoughts along these lines, including the following specific mark-up implied generic properties across all microformats (based on existing published markup use-cases)
    • 'p-name'
    • 'u-url'
    • 'u-photo'

flat sets of properties

What more can we simplify about microformats?

Numerous individuals have provided the feedback that whenever there is more than one level of hierarchy in a microformat, many (most?) developers get confused - in particular Kavi Goel of Google / Rich Snippets provided this feedback at a microformats dinner. Thus depending on multiple levels of hierarchy is likely resulting in a loss of authorability, perhaps even accuracy as confusion undoubtedly leads to more errors. Thus:

Proposal: simplify all microformats to flat sets of properties.

What this means:

• all microformats are simply an object with a set of properties with values.
• no more subproperties- drop the notion of subproperties.
• use composition of multiple microformats for any further hierarchy, e.g. the "location" of an hCalendar event can be an hCard, or the "agent" of one hCard can be another hCard.

For example for hCard this would mean the following specific changes to keep relevant functionality:

• drop "n", promote all "n" subproperties to full properties
  • given-name, family-name, additional-name, honorific-prefix, honorific-suffix
• treat "geo" as a nested microformat
• treat "adr" as a nested microformat (what to do about adr's "type"?)
• treat "org" as a flat string and drop "organization-name" and "organization-unit" (in practice rarely used, also not revealed or ignored in contact management user interfaces - e.g. Address Book)

Example: add a middle initial to the previous example Chris Messina's name, and markup each name component:

<h1 class="hcard">
 <span class="fn">
  <span class="given-name">Chris</span>
  <abbr class="additional-name">R.</abbr>
  <span class="family-name">Messina</span>
 </span>
</h1>

Note:

1. use of an explicit span with "fn" to markup his entire formatted name
2. use of the abbr element to explicitly indicate the semantic that "R." is merely an abbreviation for his additional-name.

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.

• See: issues#class-collisions

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.

COMMUNITY and TOOLS

The second most important constituency in the microformats community are the developers, programmers, tool-makers.

A non-trivial number of them 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.

existing microformats parsing requirements

COMMUNITY and TOOLS (that) USE MICROFORMATS

• parser / parsing
• structured
• getting the data out
• json - 1:1 mapping

parsing microformats currently requires

1. a list of root class names of each microformat to be parsed
2. 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
3. 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).

naming conventions for generic parsing

I think 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.
• "e-*" for 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 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.

See microformats-2-prefixes for further thoughts and discussions on these and other class prefixes.

Example: taking that simple heading hCard example forward:

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

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. See microformats-2-prefixes for documentation of existing single-letter class name prefixes in practice.

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:

<h1 class="h-card">
 <span class="p-fn">
  <span class="p-given-name">Chris</span>
  <abbr class="p-additional-name">R.</abbr>
  <span class="p-family-name">Messina</span>
 </span>
</h1>

with a hyperlink to Chris's URL:

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

COMPATIBILITY

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

Here is a simple example:

<h1 class="h-card vcard">
 <span class="fn">Chris Messina</span>
</h1>

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 DRY principle.

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

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

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 Wikipedia: HTTP header fields - non-standard headers (could use RFC reference instead) respectively, like:

• application/x-latex (per Wikipedia Internet media type: Type x)
• x-spam-score (in email headers)
• X-Pingback (per 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 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 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

• CSS 2.1 4.1.2.1 Vendor-specific extensions
• IETF MIME/content-type "x-*" extensions per RFC 2045 Section 6.3. [1]
• IETF MIME experimental fields (e.g. x-spam-score)
• HTTP header extensions (e.g. x-pingback)
• note also some critical thoughts from mnot

USERS

Need more tools and interfaces that:

• publish
• copy/paste
• right-click on a microformat
• share
• search results

discussed some existing like: H2VX converts hCard to vCard, hCalendar to iCalendar

how would we re-implement Live Clipboard today, making it easier for publishers and developers?

SEE ALSO

• microformats-2
• microformats-2-brainstorming - moving more experimental / undeveloped / and rejected thoughts ideas here to simplify/progress *this* page further.
• microformats-2-prefixes
• microformats-2-faq