Mike Dean has announced a new language version of DAML+OIL supporting W3C XML Schema datatypes.

The March 2001 edition of the DAML+OIL language version has been edited by the joint committee for the US DAML (DARPA Agent Markup Language) and European OIL (Ontology Inference Layer) projects and emphasis is put on the work done to support the W3C XML Schema datatypes:

The major new features are support for XML Schema data types and improved documentation.

This support appears in the language specification itself, the "nonNegativeInteger" datatype being used as a rdfs:range for RDF properties:

<rdfs:range rdf:resource="http://www.w3.org/2000/10/XMLSchema#nonNegativeInteger"/>

The annotated ontology markup further explains how to reference a W3C XML Schema user defined datatype as a class (http://www.daml.org/2001/03/daml+oil-ex-dt being a W3X XML Schema and over59 a datatype defined in this schema):

<daml:hasClass rdf:resource="http://www.daml.org/2001/03/daml+oil-ex-dt#over59"/>

Namespaces prefixes being shortcuts for their URIs, W3C XML Schema datatypes can also be used through their qualified names:

<shoesize><xsd:decimal rdf:value="9.5"/></shoesize>

This specification appears then to be a great example showing how namespaces, W3C XML Schema, RDF, RDF Schema and XPointer (http://www.daml.org/2001/03/daml+oil-ex-dt#over59 is also an XPointer expression) can fit together.

This harmony is unfortunately very superficial as explained by Jonathan Borden:

The only problem is that this version of DAML+OIL uses the wrong namespace for XML Schema, the RDFism: http://www.w3.org/2000/10/XMLSchema# -- while this 'works' for RDF the trailing '#' means that it is a completely different namespace ... that is, namespace names cannot be sort of equal, or almost equal, they either are or are not equal.

Another problem relates to the assignment of URIs for XSD types which are specified as QNames. This issue has been gone over in detail and while I have discussed some small changes that IMHO ought be made to the RDF XML syntax, the RDF and XML Schema typing mechanisms are unfortunately incompatible as they currently stand.