(sorry for X-posting, can WG chairs indicate on which list this discussion
is best placed?)

On Thu, 10 Feb 2005, Andy Powell wrote:

>
> Owners of such terms have to explicitly acknowledge that the terms are RDF
> properties (or at least declare them in such a way that they are able to
> be treated as RDF properties) before they can be used in DC application
> profiles.  In practice, I suggest that this means that the semantics of
> these terms should be declared using RDFS.

I think your bracketed statement needs more explanation... it would be
helpful to be clear as to how terms can be 'declared in such a way' that
they can be used as RDF properties. Even allowing for the constraints of
the DC data model, there seems to me some wriggle room to enable mixing
and matching where 'owners' of terms are willing to co-operate.

As I understand it the process for re-use of MARC relator terms was an
initial agreement that (some of) the relator terms would be useful within
DC records, then going through the formality of 'declaring' such terms as
RDF properties - not trying to match the MARC data model to DC data model.

......
.....

> As an example of how this can work I would cite the MARC relator terms -
> where the Library of Congress have taken (are taking?) the time to
> explicitly re-declare an existing set of terms as RDF properties.
> Because this has been done, it is now (or very soon will be) possible to
> use the MARC relator terms in a DC application profile and for that usage
> to be maningful in terms of the DCMI Abstract Model.
>

I think it is the fact that the owner is willing to declare these
terms 'outside' the rest of the MARC data model, as RDF properties that
makes it ok to mix and match? within the MARC data model and MARC records
the relator terms do not act as 'properties' as I understand it - the
terms have a different role in MARC records than within DC records.

This seems to make declaring terms as RDF properties something of a
formality - as long as the maintainer or 'owner' of data element sets is
willing to declare a particular sub-set of terms as RDF properties then
that is ok...

In my view the criteria for re-use of terms should be something like:

"First, are the semantics and context of a term in one metadata format
sufficiently similar to the semantics and context of the property I want
to express in a DC description? if so can this term be usefully used in
'isolation' within a DC description out of the context of its original
format?

Second, are the 'owners' of the terms willing to co-operate?"

If the answer to both of the above is yes, then declaring those terms as
RDF properties may well be achievable. Especially if, as I understand has
happened with MARC relator terms, just the sub-set of terms required from
the 'other' format based on a different data model need to be declared??

Maybe worth thinking about that old saying 'everything can be solved by a
level of indirection'.... not knowing much about MODS, but could a sub-set
of MODS terms be 'separated out' of MODS and declared as RDF properties?

In my view we should be looking for solutions to help us meet requirements
of several user communities, and to move forward as regards the evolution
of data element sets by allowing re-use of data elements. If this can be
done by declaring sets of terms in RDFS then good....

Rachel


---------------------------------------------------------------------------
Rachel Heery
UKOLN, University of Bath                       tel: +44 (0)1225 386724
http://www.ukoln.ac.uk