Toby Inkster beschreibt auf seinem Blog sehr anschaulich, wie man eine hCard mit RDFa-Informationen erweitern kann.
While hCard offers many useful properties that can be used to describe contacts, some are considered beyond the scope of the hCard specification. For example, there is no hCard property to mark up somebody’s height, or shoe size.
This is where RDFa comes in. RDFa is not a specialist format for describing people or organisations, but a more general format for describing anything. We can use RDFa to add in the extra information we want.