At the risk of re-opening old arguments....
http://www.jiscmail.ac.uk/cgi-bin/wa.exe?A2=ind0205&L=dc-architecture&T=
0&F=&S=&P=1996
and the dozens of messages which followed.... I would just like to
clarify that my interpretation is correct.
(After this, I won't mention it again... I promise...)
In the DCMI RDF schemas we currently have statements like, e.g.
<http://purl.org/dc/elements/1.1/title>
<http://www.w3.org/2000/01/rdf-schema#isDefinedBy>
<http://purl.org/dc/elements/1.1/> .
and a bunch of stuff about <http://purl.org/dc/elements/1.1/> which
includes:
<http://purl.org/dc/elements/1.1/>
<http://purl.org/dc/elements/1.1/title> "The Dublin Core Element Set
v1.1 namespace providing access to it's content by means of an RDF
Schema." .
As far as I can see, there's no rdf:type specified for the resource
<http://purl.org/dc/elements/1.1/>
My understanding of the outcome of the long debate about
rdfs:isDefinedBy was that the value can be _any_ resource which in some
unspecified way or other "defines" the subject resource.
1. In the case of the DCMI descriptions, that second defining resource
is (I think - please correct me if I'm wrong) an RDF/XML document, a
schema (in the sense of a machine-readable representation of the DCMI
terms), i.e. if we did specify a type for
<http://purl.org/dc/elements/1.1/>, it would be a resource of type
dcmitype:Text (and not an "abstract" resource of type something like
"namespace", if such a type existed).
However, I _could_ have a non-RDF/XML document as the object of an
rdfs:isDefinedBy statement: an HTML document, a text file, a graphic,
even a non-Web retrievable resource. Is that correct please?
2. Also in the DCMI case, that "defining" RDF/XML document is
retrievable using HTTP GET with a URI, and that URI is also used as an
XML namespace name in the RDF/XML syntax (i.e. "the schema is at the
namespace URI").
However, that is a convention, and there is no _requirement_ that the
identifier of the "defining" resource (the identifier of the object of
an rdfs:isDefinedBy statement) coincides with an XML namespace name used
in the RDF/XML representation. Is that correct please?
i.e. My understanding is that given that the PURL
http://purl.org/dc/elements/1.1/ redirects to
http://dublincore.org/2002/08/13/dces# , and leaving aside the issue of
persistence, that second URL could equally well be used in the schemas:
something like:
<http://purl.org/dc/elements/1.1/title>
<http://www.w3.org/2000/01/rdf-schema#isDefinedBy>
<http://dublincore.org/2002/08/13/dces#> .
[etc]
and
<http://dublincore.org/2002/08/13/dces#>
<http://purl.org/dc/elements/1.1/title> "The Dublin Core Element Set
v1.1 namespace providing access to it's content by means of an RDF
Schema." .
without ever making _any_ statements involving the resource identified
by http://purl.org/dc/elements/1.1/ .
I'm _not_ suggesting we should do that for these schemas: I just want to
clarify that my understanding is correct and it would be a valid use of
rdfs:isDefinedBy ;-)
Thanks
Pete
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Pete Johnston
Interoperability Research Officer
UKOLN, University of Bath, Bath BA2 7AY, UK
tel: +44 (0)1225 383619 fax: +44 (0)1225 386838
mailto:[log in to unmask]
http://www.ukoln.ac.uk/ukoln/staff/p.johnston/
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