Knowing what RDFA vocabulary to use
There are many vocabularies. And you could create your own, too, of course (but you probably shouldn’t before you checked possible alternatives). You’d have to look for vocabularies for your specific needs, for example by browsing and searching on http://lov.okfn.org/dataset/lov/ (they collect and index open vocabularies), on W3C’s RDFa Core Initial Context (it lists vocabularies … Read more