XHTML+RDFa and auto discovery

I was thinking more about the Steven's words (in my previous thread)
regarding xhtmlvocab:alternative and rdfs:seeAlso and started to wonder how
is data discovery going to be adopted by developers writing RDFa client
software.

While not strictly RDF(a), it should probably be part of XHTML+RDFa
discussion.

I see that W3C RDFa distiller (http://www.w3.org/2007/08/pyRdfa/) adds
sometriples from
http://www.w3.org/1999/xhtml/vocab# indicating alternate documents, style
sheets and so on.

While this might be left to the user to decide what they want to use, it
might be a good idea to have some sort of best practices, recommendations or
even standards for RDFa parser developers to use so they provide this data
to the end-developers (developers who're end-users of APIs).

I wonder if any such specification / best practices document exists already?
I cound't find anything like that on test harness page or implementation
report:

   - http://rdfa.digitalbazaar.com/rdfa-test-harness/
   - http://www.w3.org/2006/07/SWD/RDFa/implementation-report/

Also in addition to having parsers returning this data, are there any best
practices for developers on how to use this data for joining with other RDF
sources (either pure RDF or RDFa documents in other languages and so on?

I hope to write some RDF(a) clients soon and will be happy to be a guinea
pig for testing best practices on ;)

Will appreciate any feedback!

Thank you,

        Sergey


-- 
Sergey Chernyshev
http://www.sergeychernyshev.com/