Re: A new version of Characterisation XML schema

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
>
>
>

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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