On Wed, May 29, 2002 at 08:06:36PM +0200, Roland Schwaenzl wrote:
> > +++| <rdf:Property rdf:about="http://purl.org/dc/terms/alternative">
> > +++| <rdfs:label xml:lang="en">Alternative</rdfs:label>
> > +++| <rdfs:comment xml:lang="en">Any form of the title used as a substitute or
> > +++| alternative to the formal title of the resource.</rdfs:comment>
> > +++| <dc:description xml:lang="en">This qualifier can include Title
> > +++| abbreviations as well as translations.</dc:description>
> > +++| <rdfs:subPropertyOf rdf:resource="http://purl.org/dc/elements/1.1/title"/>
> > ---| <rdfs:isDefinedBy rdf:resource="http://purl.org/dc/terms/"/>
> > +++| <dcterms:issued>2000-07-11</dcterms:issued>
> > | </rdf:Property>
..
> > The RDFS representation lacks information on Status, Term Type,
> > and Versioning (VMS-ID, Decision, Date modified, Supersedes). If the
> > schema is sufficient as support for RDF applications, this means that
> > an RDF application would not need these things?
>
> It has dcq:modified, where modifications are known to the public.
> As the integrity of applications requires existing terms never change semantics,
> modifications are limited to changes of non-vital properties of the resources.
I'm not following you here... The RDFS term declaration for
"alternative" (above) does not have dcterms:modified, only a
dcterms:issued. It is true that the namespace policy limits
the scope of modifications to things that do not fundamentally
alter the semantics of a term, but Section III of that policy
also requires any change to a term declaration, no matter how
trivial, to be reflected in versioning information: "In all
(!) cases, any (!) changes to DCMI terms or term declarations
will result in an update to the versioning information carried
in the DCMI recommendation and/or DCMI term declaration
associated with that term." This is the guideline I have
been following in developing the documentation posted at
http://www.gmd.de/People/Thomas.Baker/usage/terms/dc/.
> > According to http://www.w3.org/2000/01/rdf-schema,
> > "isDefinedBy" means "Indicates a resource containing and
> > defining the subject resource".
>
> http://www.w3.org/TR/2000/01/CR-rdf-schema-20000327/#s2.3.5
> should clarify your concern.
> [It mentions dc explicitly].
Hmm, I get "Sorry not found."
> > I am confused because
> > I think of "alternative" as being uniquely _identified_
> > by the string http://purl.org/dc/terms/alternative but
> > actually _defined_ and documented in the Web resource
> > http://dublincore.org/usage/terms/dc/ (to be precise, at
> > http://dublincore.org/usage/terms/dc/#alternative-002).
>
> DC has in a formal fashion defined, what it's namespace URI's
> are. Before the DCMI namespace rec was made one could have
> argued as you do. It's an advantage for DC to have this standard.
This gets back to the basic distinction between "canonical"
(or "authoritative" or "definitive") representations of DCMI
terms and representations derived from the same, such as an
RDF schema.
If I have correctly understood you (and Harry), the intention in
creating an RDF schema is not to provide "the" definitive
representation -- that is provided currently by Recommendation
documents on the DCMI Web site, in the near future by the
Usage-Board-maintained text files I am editing, and in the
medium term perhaps by a VMS database -- but merely to present
the definitive semantics in a form usable by RDF applications.
> > > [This doesn't say, that all RDF applications will just use
> > > such a slim version. ]
Then I have correctly understood that this particular RDF
schema is but one possible representation among others, even
other RDF schemas.
> > I am assuming that one could declare the "missing" information
> > from my text description as RDF assertions as well...
>
> That's not the point.
..
> How the vocabulary management system is supposed to
> work internally is not my current business.
If the RDF schema is not presented as, and does not declare
itself to be, the canonical representation, then I agree that
loading versioning information into that schema may indeed not
be the point.
However, I am very much concerned by the following construct,
taken as a whole:
1) a Namespace Policy saying that DCMI terms are (in effect)
canonically identified by URIs; together with
2) a resolver that resolves the namespace URIs to an RDF
schema (as suggested by Harry); together with
3) an RDF schema in which each term declaration says it
"isDefinedBy" the very same namespace URI; and
4) in which the term declarations do not declare or point to the
full historical versioning information of each term but in fact
present a subset of the fuller information derived from
some other set of documents or from a vocabulary management
system.
To me, such a construct is misleading because it creates a
self-referential circle, saying in effect that "DCMI declares
this RDF schema to be _the_ definitive representation." Whereas
-- as you have yourself confirmed -- the RDF schema is but "a"
definitive representation.
If the semantics of "rdfs:isDefinedBy" dictate that it be used
simply to point to the namespace within which the individual
terms are situated, then "isDefinedBy" should by all means be
used that way. But in that case, in my opinion, the property
declaration should include some sort of pointer to the
definitive resource from which that particular representation
was derived and where the versioning information may be found.
Tom
--
Dr. Thomas Baker [log in to unmask]
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