There may be some technicalities with XML schema that makes this true that
I don't know. But I thought that the real issue is whether you can
identify a metadata element with a URI. If you can, then you could use it
in another schema. We have been involved in an agreement (CORES) to
provide URIs for our metadata elements. This would apply to MARC elements
as well as MODS element. For the moment, we would start with giving a
policy for assignment of persistent URIs for elements. In the future, we
would mark up our documentation explicitly using these URIs for the
elements. So, in fact, there are MODS elements that are used in the
DC-Library application profile for the reasons you suggested: that they
are metadata elements already defined and just as though they can be
referenced with a URI they could theoretically be used.

The article in D-Lib magazine is:
In the article it gives some examples of likely assignments. One is:
So we've used this convention to refer to a subelement.

The elements in the DC-Library application profile that are referenced
(I admit, there is yet no schema for DC-Lib AP.)

In the case of Dublin Core, the documentation does assign URIs for
elements, which I think is the reason they can be used globally. In any
case, Dublin Core is flat and there is no hierarchy in the elements, which
is another reason why all the elements are "global". The hierarchy in MODS
is not something we would want to drop.

We do have some further work to do to make all this implementable. But I
do think the important thing is the ability to reference the element-- and
then you would include the namespace of course in any instance or schema
that uses the MODS elements.


On Wed, 5 Nov 2003, Robin Wendler wrote:

> Could I beg for a little Schema for Dummies advice?
> Did the MODS schema authors consider making more of
> the MODS subelements global elements, and "ref-ing" them
> within the larger elements such as originInfo?
> The reason I ask is that in trying to draft an Eresources Management
> schema for the DLF ERM Initiative, I would prefer to incorporate
> MODS elements rather than define brand new ones where there is overlap.
> Unfortunately, XML schema only permits the referencing of global elements,
> when what the ERM data dictionary calls for correspond to subelements of
> MODS such as publisher and frequency. For example, ERM doesn't
> need "place", but I do want to be able to specify which pieces of originInfo
> ERM records should use. I can't even "ref" originInfo, either because it is
> not global, is a complexType or both. (I wonder if the xlink and Dublin Core
> schemas were created the way they were expressly to facilitate the reuse of
> their elements in other schemas.)
> Is there another technique that would permit the use of specific MODS
> subelements within another schema? The concepts I want are in MODS, but
> I haven't found a way to use them.
> The usual apologies for asking dumb questions apply. Thanks,
> --Robin
> Robin Wendler
> Harvard University Library
> Office for Information Systems
> 1280 Massachusetts Ave., Suite 404
> Cambridge, MA 02138 USA
> 617-495-3724 (W)
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