RDFa provides a set of XHTML attributes. RDF is stored in triples not RDFa. RDFa is simply a representation of RDF, a syntax for representing RDF triples. Once an RDF vocab is created you can just use it in RDFa, just like existing vocabularies. You still have to create an RDF schema for RDFa for particular data. The argument is usually RDF(a) vs Microformats. Google supprts both and XFN
