Concrete Types Proposal

This is a proposal for adding concrete data types (essentially subtypes of rdfs:Literal) to DAML-OIL. It was developed by Mike Dean and presented to the Joint Committee on 19 December 2000.



  1. Allow use of an XML Schema Datatype URI as the range of a property. Such a URI may be either
    1. a reference to a builtin data type defined by the standard, e.g.
    2. a reference to a user-defined derived type contained in an appropriate XML document type, e.g.
  2. Such URIs will implicitly be considered subclasses of rdfs:Literal.
  3. DAML components may make use of the range constraint (and any other information derivable from it, e.g. by retrieving the referenced XML Schema definition), or may behave as if rdfs:Literal were specified instead (i.e. just treat the value as a string).


Application-specific XML Schema types defined in example.xsd.

Simple ontology using these types defined in example-ont.daml.


  1. This approach (explicitly) doesn't support reasoning about types at the DAML language level.
  2. What is now the range of range? Should it still include rdfs:Literal? Was rdfs:Literal ever really a Class? (Making types implicit subclasses of rdfs:Literal means that the range of range doesn't have to change.)
  3. Can we replace DAML lists with XML Schema lists? That should provide stronger typing of the list elements (itemType).

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