DC comments & questions

[Tony Linde]

Hi Bob, Roy et al,

I checked out PDS profiling yesterday and their use of DC. It is similar to
ours but they're using their own element descriptive language (keyword=value
based) where we're using xml schema. PDS cannot therefore use inheritance
and other features of xml schema that we're making use of. 

PDS have implemented a sort of registry browser with cross-links between
missions, datasets, hosts, instruments etc and with links from keywords to
help text and enumerations. A really good utility that we'd do well to
emulate.

The PDS seem to only have ued Identifier, Title and Format from DC. It also
seems a fairly recent adoption as many of the actual products I found did
not have these as part of the metadata but I might have been looking at the
wrong things.

I also looked into DC closer today and have a few questions:

1. I see in the schemas that DC-related elements are annotated with
<vm:dcterm> elements - how are these to be used? And ought we to be
namespacing to DC instead?

2. Where, with things like identifier and coverage, we have structured data
while DC mandates simple string data, how and where does this conversion
take place?

3. Should we, like PDS, block all our DC terms into a single complex type? 

4. If so and where our metadata does not map to a simple string, should we
put the DC term in here and mandate that it is not captured from the
user/dataaset but is constructed from the structured metadata in some way
(as we've defined the way of turning an Identifier into a URI)?

5. Finally, how do we use DC? When metadata from our registries is harvested
to non-astro sites, what do they take: only the DC terms or all of the
metadata? And how is OAI related to DC?

Cheers,
Tony. 
__
Tony Linde                       Phone:  +44 (0)116 223 1292
AstroGrid Project Manager        Fax:    +44 (0)116 252 3311
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University of Leicester          Email:  ael at star.le.ac.uk
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