ADEC and VO data registration

[Arnold Rots]

In the interest of simplicity for authors, can anyone explain what the
advantage is of this three-element Identifier definition:

        <AuthorityId>/<ResourceKey>#<DatasetId>

which would result in things like:

        Sa.CXO/4000
        Sa.HST/STIS#O4LT010E0
        Sa.HST/WFPC2#U32L0104T
        Sa.IUE/LWP25899

Over the two-element identifier:

        <AuthorityId>/<DatasetId>

that would result in identifiers like:

        Sa.CXO/4000
        Sa.HST.STIS/O4LT010E0
        Sa.HST.WFPC2/U32L0104T
        Sa.IUE/LWP25899

In both cases the same number of resources have to be registered,
though in the first case they are all different authority Ids, while
in the first case some of them are resource keys.
Actually, come to think of it, the first case requires more registry
records since the authority Ids as well as the resource keys need to
be registered.
In either case Sa.HST.STIS and Sa.HST/STIS need to be resolved to a
physical location.  What's the difference?

I don't see any advantage and unless someone can convince us that it's
a much better idea, I propose that we drop the #-sign and return to
the two-element model - it's simpler and cleaner.

  - Arnold

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Arnold H. Rots                                Chandra X-ray Science Center
Smithsonian Astrophysical Observatory                tel:  +1 617 496 7701
60 Garden Street, MS 67                              fax:  +1 617 495 7356
Cambridge, MA 02138                             arots at head-cfa.harvard.edu
USA                                     http://hea-www.harvard.edu/~arots/
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