metaformats specification

metaformats is an extension to the microformats2-parsing for parsing invisible data published in HTML meta tags, both with an explicit methodology, and for backward compatibility with existing vocabularies that have multiple testable interoperable implementations.

This is a Living Specification that is subject to change as research discovers meta tag vocabularies in wide use and consumed by multiple implementations. This specification has no stable portions. Features are untested, unless explicitly labeled stable, draft, or proposed, or in stable, draft, or proposed sections. All features are likely to change. Stable features are possible, and thus this living specification may eventually document some. When stable features are documented, substantive changes may be proposed by issues and errata filed in response to implementation experience, requiring consensus among participating implementers as part of an explicit to be defined change control process.

Participate

Open Issues

IRC

Editor

Tantek Çelik

License

Per CC0, to the extent possible under law, the editors have waived all copyright and related or neighboring rights to this work. In addition, as of 2024-12-22, the editors have made this specification available under the Open Web Foundation Agreement Version 1.0.

Initial publication

2022-04-01

algorithm changes

For each of the following subsections, apply the changes therein to the steps in the same subsection in the microformats2-parsing specification.

parse a document for microformats

Change the line "start with an empty JSON…" to:

• start with an empty JSON "items" array and hashes "meta-item", "rels", "rel-urls":

Update the JSON sample data structure to:

{
 "items": [],
 "meta-item": {},
 "rels": {},
 "rel-urls": {}
}

Before the line "* return the resulting JSON", insert:

• parse the head element for backcompat metaformats

parsing an element for properties

parsing a p- property

insert before "else return the textContent of the element after …":

• else if meta.p-x[content], then return the content attribute

parsing a u- property

insert before "else return the textContent of the element after …":

• else if meta.u-x[content], then get the content attribute

parsing a dt- property

insert before "else return the textContent of the element after …":

• else if meta.dt-x[content], then return the content attribute

parse the head element for backcompat metaformats

After the section "parse an img element for src and alt", insert a new sibling section:

=== parse the head element for backcompat metaformats ===

With the following instructions:

• if there were no root class names found on the html and head elements
  • if there is a meta[property=og:type] then
    • get that meta element’s content attribute value
    • if it’s "article" then set the meta-item "type" property to "entry"
    • if it’s "profile" then set the meta-item "type" property to "card"
    • if it's "music" or "video" then set the meta-item "type" property to "cite"
  • end if
  • if there is no meta-item "type" property value and there is a meta[name=twitter:card] then
    • get that meta element’s content attribute value
    • if it's "summary" or "summary_large_image" then set the meta-item "type" property to "entry"
  • end if
  • if there is no meta-item "type" property value and
    • there is a meta[property^=og:] or meta[name^=twitter:]
  • then set the meta-item "type" property to "entry"
  • parse meta elements for backcompat properties as follows and add them to a "properties" hash inside the "meta-item" hash:
    • if meta[property="og:title"], parse content attribute as p-name
    • else meta[name="twitter:title"], parse content as p-name
    • if meta[property="og:description"], parse content as p-summary
    • else if meta[name="twitter:description"], parse content as p-summary
    • if meta[property="og:image"], parse content as u-photo
    • else if meta[name="twitter:image"], parse content as u-photo
    • if meta[property="og:video"], parse content as u-video
    • if meta[property="og:audio"], parse content as u-audio
    • if meta[property="article:published_time"], parse content as dt-published
    • if meta[property="article:modified_time"], parse content as dt-updated
    • if meta[property="article:author"], parse content as p-author
  • end if /* parse meta elements for backcompat properties */
• end if /* no root class names found on html and head */

Background

The following prior work was used to develop this specification:

• IndieWeb: metaformats page
• metaformats-brainstorming

See Also

• microformats2-parsing
• meta