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Re: Syntax and Primer: URI for XML Schema

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Thu, 12 Dec 2002 20:37:18 +0000
To: Art.Barstow@nokia.com
cc: www-rdf-comments <www-rdf-comments@w3.org>
Message-ID: <29730.1039725438@hoth.ilrt.bris.ac.uk>

>>>Art.Barstow@nokia.com said:
> Why do the Primer and Syntax docs both use:
>  http://www.w3.org/2001/XMLSchema# ...
> as the base URI in the examples of rdf:datatype usage?

We are following:

  [[3 Built-in datatypes

   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

Since RDF/XML needs to construct the URIs from an XML namespace and a
local name, that convienently gives:
  namespace URI  http://www.w3.org/2001/XMLSchema#
  local name     int

and in the N-Triples for the datatype, the full URI.

> Rather than perhaps:
>  http://www.w3.org/2001/XMLSchema-datatypes
> which Syntax uses in the RELAXNG Compact Schema?

RELAXNG understands namespaces - they are in the model of RELAXNG.
RDF's model, a graph as triples, has no namespaces, but does have
URI-refs.   RELAXNG can thus use the next section of ibid:

  [[3.1 Namespace considerations

  To facilitate usage in specifications other than the XML Schema
  definition language, such as those that do not want to know
  anything about aspects of the XML Schema definition language other
  than the datatypes, each .built-in. datatype is also defined in the
  namespace whose URI is:

    * http://www.w3.org/2001/XMLSchema-datatypes

"in the namespace" has no meaning in the RDF graph; it doesn't deal
with names-in-a-set but triples of nodes.

There are two sets of terms that are generally called the RDF
namespaces - rdf and rdfs, but those are merely sets of URI-references.

Received on Thursday, 12 December 2002 15:40:05 UTC

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