Facebook OpenGraph with HTML5 validation test page

This page is HTML5, includes Facebook OpenGraph tags and a Like button:

It fails to validate as HTML5 because it uses the xmlns attribute to declare namespaces and xmlns is not allowed in HTML5 documents.

The RDFa part validates with check.rdfa.info.

Try it without the Facebook OpenGraph metadata.

Links

• View Roller source
• Edit Roller source
• There is also an XHTML version of this page

Related

• Facebook dev forum: HTML pages (not XHTML pages) and "meta properties" vs "meta name"
• Facebook dev forum: "property" attribute?
• rdfa.info: How to validate RDFa

Possible RFE/bug reports

• Facebook: explain how to use the OpenGraph tags in valid HTML, which Doc-Types to use, etc.
• RDFa workgroup: close issue of HTML5, which is still open as of June 2010.
• RDFa workgroup: provide HTML and XHTML Doc-Types DTDs that permit iframes.