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Mikael Nilsson wrote: > Well, I sort of agree, but not completely. > > According to RDF, a Datatype is also a Class, that is > > rdfs:Datatype rdfs:subClassOf rdfs:Class > > For example, xsd:date (which is a Datatype) is also a class. > > That means that all Datatypes can be used as the class of a value, i.e. > in the position of a vocabulary encoding scheme. Which I did in my > example. > > However, it is *not* true that all classes are Datatypes. The class > foaf:Person is clearly not, for example. Such classes are *not* valid as > Syntax encoding schemes. Yes, agreed. > So being a syntax encoding scheme means more than being a vocabulary > encoding scheme, in my opinion. Oh, yes, I agree. I didn't mean to suggest that the distinction between classes and datatypes or that between "vocabulary encoding scheme" and "synatx encoding scheme" wasn't important. I was suggesting only that we need to think of "vocabulary encoding scheme" and "syntax encoding scheme" as "roles"/"functions"/"positions" (using your term above) that classes and datatypes "perform"/"occupy" in statements The role/position of "vocabulary encoding scheme" may be occupied by a class (which might also be a datatype, but might not be) and the role/position of "syntax encoding scheme" may only be occupied by a datatype. But making a global assertion that some resource "is a vocabulary encoding scheme" (etc) doesn't seem quite right, because it suggests (to me, at least) that they will always (only?) be "in that role/function/position", which isn't the case. Pete -- Pete Johnston Research Officer (Interoperability) UKOLN, University of Bath, Bath BA2 7AY, UK tel: +44 (0)1225 383619 fax: +44 (0)1225 386838 mailto:[log in to unmask] http://www.ukoln.ac.uk/ukoln/staff/p.johnston/