W3C home > Mailing lists > Public > public-owl-wg@w3.org > November 2007

Re: A brief primer on Qnames and URIs

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Thu, 15 Nov 2007 05:45:30 -0500 (EST)
Message-Id: <20071115.054530.235781452.pfps@research.bell-labs.com>
To: bparsia@cs.man.ac.uk
Cc: public-owl-wg@w3.org

Summary:  There are approved URIs for the XSD facets.  

Result:  I think that thus we can use the XSD names for the XSD facets
	 in OWL 1.1.


From: Bijan Parsia <bparsia@cs.man.ac.uk>
Subject: A brief primer on Qnames and URIs
Date: Thu, 15 Nov 2007 02:21:34 +0000

[...]

> Currently, afaik, XML Schema does not provide URIs for datatype  
> facets, although it does provide QNames. If we are going to make uris  
> out of xsd:minInclusive, then we are *coining* those uris. They are  
> easy to coin, but we're still doing something (and not merely reusing  
> something XML Schema has done.)

Wow, I misremembered the situation.  There are approved URIs for the
facets, and this has been the case since 2001.

From http://www.w3.org/TR/xmlschema-2/ and also in
http://www.w3.org/TR/xmlschema11-2/

***************

Each built-in datatype in this specification (both ·primitive· and
 ·derived·) can be uniquely addressed via a URI Reference constructed
 as follows:

   1. the base URI is the URI of the XML Schema namespace
   2. the fragment identifier is the name of the datatype

For example, to address the int datatype, the URI is:

    * http://www.w3.org/2001/XMLSchema#int

Additionally, each facet definition element can be uniquely addressed
via a URI constructed as follows:

   1. the base URI is the URI of the XML Schema namespace
   2. the fragment identifier is the name of the facet

For example, to address the maxInclusive facet, the URI is:

    * http://www.w3.org/2001/XMLSchema#maxInclusive

Additionally, each facet usage in a built-in datatype definition can be
uniquely addressed via a URI constructed as follows:

   1. the base URI is the URI of the XML Schema namespace
   2. the fragment identifier is the name of the datatype, followed by a
   period (".") followed by the name of the facet

For example, to address the usage of the maxInclusive facet in the
definition of int, the URI is:

    * http://www.w3.org/2001/XMLSchema#int.maxInclusive

***************

Note, however, that the URIs for the datatypes are *not* the
concatenation of their namespace http://www.w3.org/2001/XMLSchema and
their local name.  For example the URI for integer is
http://www.w3.org/2001/XMLSchema#integer, not
http://www.w3.org/2001/XMLSchemainteger.  One would thus expect that in
an OWL or RDF document that the namespace for prefix xsd would be
http://www.w3.org/2001/XMLSchema# and not the XML Schema namespace.

I wonder what the "unique" bit above is all about.  Is the document
saying that *any* reference to the built-in type integer has to be via
http://www.w3.org/2001/XMLSchema#integer?  This seems to be a large
amount of hubris to me.


> Cheers,
> Bijan.
> 
> P.S. XML Schema 1.1 refers to the component designator WD:
> 	http://www.w3.org/TR/xmlschema11-1/#ref-scds

Yes, but only to say that SCDs are out of scope.

peter
Received on Thursday, 15 November 2007 10:59:08 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 8 January 2008 14:13:27 GMT