How does RDF get extended to new datatypes?

I think we still have a datatype issue that needs a little thought. 

The D in D-entailment is a parameter. Although RDF is usually treated as having its own special datatypes and the compatible XSD types as being the standard D, it is quite possible to use RDF with a larger D set, so that as new datatypes come along (eg geolocation datatypes, or time-interval datatypes, or physical unit datatypes, to mention three that I know have been suggested) and, presumably, get canonized by appropriate standards bodies (maybe not the W3C, though) for use by various communities, they can be smoothly incorporated into RDF data without a lot of fuss and without re-writing the RDF specs. 

Do we want to impose any conditions on this process? How can a reader of some RDF know which datatypes are being recognized by this RDF? What do we say about how to interpret a literal whose datatype IRI you don't recognize? Should it be OK to throw an error at that point, or should it *not* be OK to do that? Shouid we require that RDF extensions with larger D's only recognize IRIs that have been standardly specified in some way? How would we say this? 

The current semantic story is that a literal "foo"^^unknown:datatypeIRI  is (1) syntactically OK (2) not an error but (3) has no special meaning and is treated just like an unknown IRI, ie it presumably denotes something, but we don't know what. Is this good enough? 

Pat

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Received on Wednesday, 24 April 2013 03:09:55 UTC