Topics: The time element (and microformats) | HTML5 Doctor
While HTML 5 has a bunch of semantic elements, including new ones like article and nav , sometimes there just isn’t an element with the right meaning. What we want are ways to extend what we’ve got, to add extra semantics that are machine-readable — data that a browser, script, or robot can use.
In HTML 5, rev has fallen by the wayside, becoming obsolete since hardly anyone used it correctly, and because it can be replaced by rel. profile is also obsolete, and there is no support for namespaces in HTML 5. However, meta , class , and rel are all in HTML 5. In fact, meta now has spec-defined name s and a way to submit new name values , and rel has several new link types defined in the HTML 5 specification and a way to submit more too.
Even better, WAI - ARIA ’s role and aria-* attributes are allowed in HTML 5 , and HTML 5 validators can check HTML 5+ ARIA. Other new methods of extending HTML 5 include custom data attributes ( data-* ) , microdata , and RDFa.