W3C Recommendations that extend HTML

CSS Style Attributes

Markup languages such as HTML and SVG provide a style attribute on most elements, to hold inline style information that applies to those elements. This draft describes the syntax and interpretation of the CSS fragment that can be used in such style attributes. [[css-style-attr]]

Image Description (longdesc)

This specification defines a longdesc attribute (based on the longdesc attribute of HTML 4) to link descriptions to images in HTML content. [[html-longdesc]]

Internationalization Tag Set

This specification defines

The various its-* attributes
  • its-allowed-characters
  • its-line-break-type
  • its-loc-note
  • its-loc-note-ref
  • its-loc-note-type
  • its-loc-quality-issue-comment
  • its-loc-quality-issue-enabled
  • its-loc-quality-issue-profile-ref
  • its-loc-quality-issue-severity
  • its-loc-quality-issue-type
  • its-loc-quality-issues-ref
  • its-loc-quality-rating-profile-ref
  • its-loc-quality-rating-score
  • its-loc-quality-rating-score-threshold
  • its-loc-quality-rating-vote
  • its-loc-quality-rating-vote-threshold
  • its-locale-filter-list
  • its-mt-confidence
  • its-org
  • its-org-ref
  • its-person
  • its-person-ref
  • its-prov-ref
  • its-provenance-records-ref
  • its-rev-org
  • its-rev-org-ref
  • its-rev-person
  • its-rev-person-ref
  • its-rev-tool
  • its-rev-tool-ref
  • its-storage-encoding
  • its-storage-size
  • its-ta-class-ref
  • its-ta-confidence
  • its-ta-ident
  • its-ta-ident-ref
  • its-ta-source
  • its-term
  • its-term-confidence
  • its-term-info-ref
  • its-tool
  • its-tool-ref
  • its-within-text

to support automated creation and processing of multilingual Web content. [[its20]]

Pointer Events

This specification defines a unified event model to handle mouse, touch and stylus input. It builds on mouse events, and extends the Element, GlobalEventHandlers and Navigator interfaces of HTML. [[pointerevents]]


RDFa comprises a family of specifications which specify attributes for XML, SGML, and HTML-style markup languages, and a processing model that can reliably parse RDFa information to produce RDF

An overview of the RDFa family of specifications
Formal processing and syntax rules for RDFa
HTML-specific rules and syntax for RDFa
XHTML-specific rules and syntax for RDFa
A minimal subset of RDFa, of similar size to [[microdata]]

Subresource Integrity

This specification defines a mechanism by which user agents may verify that a fetched resource has been delivered without unexpected manipulation. It adds the integrity attribute for link elements whose rel attribute value inclues stylsheet, and for script elements, and extends the HTMLLinkElement and HTMLScriptElement interfaces. [[SRI]]


This specification defines a mechanism to notify a URL that it has been mentioned. It adds the webmention value for the rel attribute of links. [[webmention]]