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Re: proposed response to Jeff Pan's response of 23 June concerning datatypes

From: Jonathan Borden <jonathan@openhealth.org>
Date: Mon, 23 Jun 2003 13:55:38 -0400
Message-ID: <0dca01c339b0$aab6f450$b6f5d3ce@svhs.local>
To: <www-webont-wg@w3.org>, "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>

Peter F. Patel-Schneider wrote:


> >
> > I am not sure about this. Usually a URI reference of this form
> > http://any.domainname/anyxsdfile.xsd#sss will be understood to denote a
> > user-defined XML Schema datatype named sss.  Even though it is not a
> > standard way in XML Schema, there is no harm adding that in OWL
(implicitly
> > require that the datatype sss be derived from one of the built-in OWL
> > datatypes). Or do we want to support more datatypes than XML Schema
> > datatypes, so we don't like the file extension xsd?
>
> Unfortunately, this would be a non-standard access mechanism.  The OWL
> specifications should not depend on this mechanism.  Also, consider what
> would happen if the XSD file had both a top-level datatype and a top-level
> attribute with this name.
...
> >
> > It is good to have more than the built-in datatypes. However, it is not
> > clear to me how this "private understand" approach works.
> >
> > [1] http://www-db.research.bell-labs.com/user/pfps/owl/semantics/
>
> One possibility would be to use the above non-standard mechanism for
> user-defined XML Schema datatypes.  Communities could have a private
> understanding to treat URI references into XML Schema documents in this
> manner.
>

The issue of URIreferences for XML Schema particles, in this case datatypes,
is significantly more complex than initially meets the eye. The XML Schema
WG is considering this issue, and we should state (at most) that OWL will
defer to the mechanism created by XML Schema WG, or simply punt on the issue
(which is what we decided.)

An example of the complexity: suppose an XML Schema datatype is defined not
in the URI specified document but in an external module _included_ by that
top level document: what ought the URIref for the datatype be? etc. etc.
etc.

I think that we, as a WG, ought formally say little on this issue, except to
ack that there is no official way to generate a URIref for an arbitrary XML
Schema datatype.

Jonathan
Received on Monday, 23 June 2003 13:55:51 GMT

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