A new version of Characterisation XML schema

[Arnold Rots]

Mireille, Francois,

Here is a response that I had prepared quite a while ago, but that got
caught up in some local delays - apologies for that.
I hope it's still useful.

Cheers,

  - Arnold


1. Is Characterisation a DM or an XML schema?
   My proposition was that the information on the CharDM is fully (or
   almost fully) contained in the STC schema.  Hence, the CharDM
   library could as easily interface with a document containing
   metadata based on the STC schema, as it could on a document based
   on a specialized CharDM schema.
   A subissue here is the question whether one needs separate elements
   for bounds and support.  My argument (which, I don't think, has
   been fully appreciated) has always been that bounds is a subset of
   support (and, in the limit, identical to support).  Hence, a single
   element "support" provides sufficient information; "bounds" is just
   another method on the "support" object.
   Alternatively, "bounds" could be considered a restricted
   instantiation of "support".

2. If there really is a necessity of having a separate Char schema, I
   believe a CharDM document based on such a schema could be produced
   from an STC document through a simple stylesheet.
   There are various other options for integrating or coodinating the
   two schemata, but one would have to assess the implications rather
   carefully.

3. In the larger picture, if separate CharDM elements are really
   required (which I am not convinced of), I wonder whether the
   general DM shouldn't develop a top-level schema dmmd.xsd that would
   specify a general DM metadata document that includes the full DM
   metadata description of the data, like:


<?xml version="1.0" encoding="UTF-8"?>
<DMmetadata xmlns="http://www.ivoa.net/xml/DM/dmmd-v1.0.xsd"
  xmlns:xlink="http://www.w3.org/1999/xlink"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.ivoa.net/xml/DM/dmmd-v1.0.xsd
    http://www.ivoa.net/xml/DM/dmmd-v1.0.xsd">

  <ObsDataLocation xmlns="http://www.ivoa.net/xml/STC/stc-v1.3.xsd"
    xsi:schemaLocation="http://www.ivoa.net/xml/STC/stc-v1.3.xsd
      http://www.ivoa.net/xml/STC/stc-v1.3.xsd">
    ...
  </ObsDataLocation>

  <Characterisation xmlns="http://www.ivoa.net/xml/CHAR/char-v1.0.xsd"
    xsi:schemaLocation="http://www.ivoa.net/xml/CHAR/char-v1.0.xsd
    http://alinda.u-strasbg.fr/Model/Characterisation/schema/characterisation.1.
0.xsd">
    ...
  </Characterisation>

  <Provenance xmlns="http://www.ivoa.net/xml/PROV/prov-v1.0.xsd"
    xsi:schemaLocation="http://www.ivoa.net/xml/PROV/prov-v1.0.xsd
      http://www.ivoa.net/xml/PROV/prov-v1.0.xsd">
    ...
  </Provenance>

</DMmetadata>


Mireille Louys wrote:
> Dear all,
> 
> 
> There is a new *documented* version of the Characterisation XML schema 
> available as both following links:
> http://www.ivoa.net/xml/Characterisation/v1.0
> http://www.ivoa.net/xml/Characterisation/Characterisation-v1.0.xsd
> 
> Comments are welcome...
> 
> Cheers,
> Mireille Louys
> 
> 
> 
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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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