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How to close issue 5.8 datatypes

From: Jim Hendler <hendler@cs.umd.edu>
Date: Tue, 17 Dec 2002 11:11:20 -0500
Message-Id: <p05200f2eba24fb372f75@[129.2.179.23]>
To: webont <www-webont-wg@w3.org>

I believe we reached consensus on how to close datatypes, but wanted 
to review the final decision.  Here is what I believe is the current 
proposal (merging Peter and Jeremy's test)


CLOSE DATATYPING AS FOLLOWS:


1/ The exchange syntax for OWL will use RDF datatyping.

2/ The abstract syntax for OWL will use <datatype><lexical> as the syntax
    for typed data values and will only allow lexical forms that are valid
    for the datatype, i.e., <xd:integer>1.5 is not a valid typed literal in
    the abstract syntax.


3/ OWL permits the use of the  XML Schema built-in non-list simple 
types, using their  canonical URI references.

The following datatypes are RECOMMENDED for use with OWL: xsd:string, 
xsd:boolean, xsd:decimal, xsd:float, xsd:double, xsd:dateTime, 
xsd:time, xsd:date, xsd:gYearMonth, xsd:gYear, xsd:gMonthDay, 
xsd:gDay, xsd:gMonth, xsd:hexBinary, xsd:base64Binary, xsd:anyURI, 
xsd:normalizedString, xsd:token, xsd:language, xsd:NMTOKEN, xsd:Name, 
xsd:NCName, xsd:integer, xsd:nonPositiveInteger, xsd:negativeInteger, 
xsd:long, xsd:int, xsd:short, xsd:byte, xsd:nonNegativeInteger, 
xsd:unsignedLong, xsd:unsignedInt, xsd:unsignedShort, 
xsd:unsignedByte and xsd:positiveInteger.

Other datatypes, including the other built-in XML Schema datatypes MAY be used.

NOTE: specific considerations with the other built-in XML Schema datatypes are:

xsd:duration,
In this version of XML Schema no equality function is defined for 
xsd:duration. This may give surprising results when combined with OWL 
cardinality constraints. Later revisions of XML Schema datatypes are 
expected to provide such a function, in which case the revised 
duration datatype would be fully appropriate for use with OWL. 
xsd:QName,
xsd:ENTITY,
These datatypes require an enclosing XML document context, which may 
not be available in a specific application scenario for an OWL 
ontology. xsd:NOTATION,
This datatype is intended for use as a base type for user defined 
datatypes. xsd:ID,
xsd:IDREF,
The use of xsd:NCName is RECOMMENDED in OWL. xsd:IDREFS,
xsd:ENTITIES,
xsd:NMTOKENS,
List valued datatypes are OPTIONAL in OWL.


4/ Cardinality restrictions in the exchange syntax for OWL will use typed
    literals, as in
              _:x rdf:type owl:Restriction .
              _:x owl:onProperty ex:foo .
              _:x owl:cardinality "5"^^xsd:decimal .

[note: I believe there was a wording change suggested here, but I 
cannot find it - can someone update this if I'm wrong]


IN ADDITION, THE FOLLOWING WILL BE ADDED TO THE ISSUES LIST UNDER THE 
CLOSING TEXT FOR ISSUE 5.7

The Working Group believes that it is important to allow user-defined 
datatypes in OWL, and to refer to them by URI.  A proposed solution 
is below, but it is possible that the XML-schema WG will propose a 
different mechanism, and thus we postpone this issue pending a 
recommendation from that group.

Proposed use of URIs for user-defined types:

   OWL can use XML Schema non-list simple types defined at the top
    level of an XML Schema document and given a name, by using the URI
    reference constructed from the URI of the document and the local name of
    the simple type.  That is, if U is the URI of an XML Schema document
    that contains,
    <xsd:schema ...>
      <xsd:simpleType name="foo">
        <xsd:restriction base="integer">
         <xsd:minInclusive value="1700">
        </xsd:restriction>
      </xsd:simpleType>
      ...
    </xsd:schema>
    then the URI reference U#foo will be that datatype.

    Implementations of OWL may choose to ignore the facets such a type.



-- 
Professor James Hendler				  hendler@cs.umd.edu
Director, Semantic Web and Agent Technologies	  301-405-2696
Maryland Information and Network Dynamics Lab.	  301-405-6707 (Fax)
Univ of Maryland, College Park, MD 20742	  240-731-3822 (Cell)
http://www.cs.umd.edu/users/hendler
Received on Tuesday, 17 December 2002 11:11:52 GMT

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