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At 19:59 17/01/2002 -0500, Jonathan Borden wrote:
>Kal Ahmed wrote:
> > I would just be interested to hear if RDDL developers considered and
> > discarded the possibility of creating a set of Published Subject
> > for a topic map-based solution (with the associated semantics) and if so,
> > why ? One potential advantage in this approach is that later changes would
> > not require additional syntax - just new PSIs and more semantics.
>I am not sure what a "Published Subject Indicator" is, so at least I did not
>consider that solution. What would that look like?
I'll let the XTM specification speak for me on that ;-)...
"A published subject is any subject for which a subject indicator has been
made available for public use and is accessible online via a URI. A
published subject indicator is therefore any resource that has been
published in order to provide a positive, unambiguous indication of the
identity of a subject for the purpose of facilitating topic map interchange
and mergeability." 
"A subject indicator is a resource that is intended by the topic map author
to provide a positive, unambiguous indication of the identity of a subject."
More concretely, the two URIs above could be used as subject indicators for
the concepts "Published Subject Indicators" and "Subject Indicators". If
TopicMaps.Org chose to publish them in order to identify those concepts (as
they define them), then they would be PSIs. XTM does define PSIs for basic
topic map constructs such as "topic" and "association" and it also provides
some PSIs for kinds of purposes (though only a couple) -
http://www.topicmaps.org/xtm/1.0/core.xtm#sort indicates the suitability of
a name string for sorting,
http://www.topicmaps.org/xtm/1.0/core.xtm#display indicates the suitability
of a name string for display.
So, how could this be applied to RDDL ? I believe that it should be
possible to create a topic with a subject indicator for the name space
being described and then to provide occurrences of that topic that link to
related resources. The types of the occurrences would be defined by other
topics which have the RDDL-defined URIs as PSIs for the resource purpose.
To say more about the resource itself, we can create a topic which regards
the resource as its *subject* and add more meta-data to that in the form of
topic characteristics (i.e. names, occurrences and relationships to other