While eRDF and RDFa look and feel much the same, there are differences in expressivity: while RDFa is complete with respect to the RDF model, not all RDF statements can be represented in eRDF. For example, in eRDF all statements have the current page as a subject (or resources defined within the current page). Further, there is no support for datatypes, which are recommended in SearchMonkey for example to provide the currency of monetary values or units.