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Fuzzy about what defines an ontologies' namespace

From: Roger L. Costello <costello@mitre.org>
Date: Wed, 26 Feb 2003 15:39:39 -0500
Message-ID: <3E5D260B.E34A185@mitre.org>
To: public-webont-comments@w3.org
CC: "Costello,Roger L." <costello@mitre.org>

Hi Folks,

The OWL Guide is somewhat unclear about what defines an ontologies'
namespace.  The Guide starts by saying that a default namespace should
be declared:

<rdf:RDF xmlns="http://www.example.org/wine#"

The Guide says that this is used to "identify the namespace associated
with this ontology".

I took this to mean that, for example, the unique identifier for the
Wine class is:

    http://www.example.org/wine#Wine

However, the Guide then followed up with a discussion of Ontology
Headers.  In the example it shows this:

    <owl:Ontology rdf:about="http://www.example.org/wine"> 

It says this about the "about" attribute:

"The about attribute will normally be the URL of the current file. If
desired, the ontology may be given a name that is a URN and independent
of a particular physical location."

This lead me to think that perhaps the "about" attribute defines the
namespace.  So, my question is this: is it the default namespace
declaration which provides the unique identifier for each class and
property defined in the ontology, or is it the "about" attribute?  As a
followup to that question: is xml:base not relevant with OWL?

Thanks!  /Roger
Received on Wednesday, 26 February 2003 15:39:47 GMT

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