RDFa

RDFa changes RDF syntax so it can be embeded into XHTML. Here is a good tutorial, part 2.
a is for attribute: href, content, rel, rev, and datatype, as well as the new about, role and property.

At its simplest, use these attributes:

	Subject	Predicate	Object
Object is a String	about	property	content or PCDATA
Object is URI	about	rel	href

for example:

<span about="http://www.snee.com/bobdc.blog/2006/12/generating_a_single_globally_u.html"
      property="dc:title" content="Generating a Single Globally Unique ID"/>

<span about="http://www.snee.com/bobdc.blog/2006/12/generating_a_single_globally_u.html" 
      property="dc:title">Generating a Single Globally Unique ID</meta>

<span about="http://www.snee.com/bobdc.blog/2006/12/generating_a_single_globally_u.html"
      rel="dc:subject" href="http://www.snee.com/bobdc.blog/neat_tricks/"/>

span is popular, but you can use any element.

You can add multiple POs to one S:

<img src="http://www.snee.com/img/myfile.jpg"
     about="http://www.snee.com/img/myfile.jpg">
  <span property="dc:subject" content="Niagra Falls"/>
  <span property="dc:creator" content="Richard Mutt"/>
  <span property="dc:format" content="img/jpeg"/>
</img>

If there is no about the document itself is the implied subject.