RDFa

RDFa allows building metadata into XHTML and other XML documents with attributes. See also RelLicense. MozCC 2 reads RDFa.

References

• http://www.w3.org/TR/xhtml-rdfa-primer/
• http://www.w3.org/2001/sw/BestPractices/HTML/2005-rdfa-syntax
• RDFa.info
• Wikipedia article

Presentations

• http://ben.adida.net/presentations/w3c-2006-04-06/html/w3c
• http://ben.adida.net/presentations/semantic-2006-03-08.pdf
• http://skimstone.x-port.net/introduction-to-rdfa

Content discovery

A key use case for RDFa is the annotation of resources included or embedded in web pages. Existing annotations apply to the current document. For example, http://example.com/foo contains

<a rel="license" href="http://creativecommons.org/licenses/by/2.5/">cc</a>

This says that http://example.com/foo is licensed under CC BY 2.5. What about http://example.com/bar.jpg which is displayed in http://example.com/foo via a &tl;img src="/bar.jpg"> element?

To specify that bar.jpg is licensed, even under a different license, we can qualify the link with an about attribute:

<a about="/bar.jpg" rel="license" href="http://creativecommons.org/licenses/by-nc/2.5/">cc</a>

Found in http://example.com/foo this says http://example.com/bar.jpg is licensed under CC BY-NC 2.5.

See beyond the current document in the RDFa primer for more examples.

The RDFa highlighter bookmarklet provides visual cues for statements about included resources.