SED Data Model: Questions and Comments

[Steve Allen]

On Wed 2005-02-16T17:56:59 +0000, David Berry hath writ:
> I'm not sure it's a good principle to duplicate information in different
> forms within a DM just to make it easier to write an interpreter. For
> instance, FITS-WCS paper II expressely says this shouldn't be done in
> the context of FITS WCS headers. The unit string has all the information
> you need, in a compact human readable form. Seems good to me.

The FITS WCS papers are examples of trying to set limits on the
pre-existing situation of almost complete chaos, but the prescriptions
of the WCS papers are only as tight as the bounds of what was
politically possible.  Although each prescription is intended to be
unambiguous, the prescriptions are necessarily broad enough to permit
them to have gained international approval.

The WCS papers should not be overly interpreted as the final word on
the subject of data characterization.  It is pretty clear that the VO
efforts will henceforth serve as the proving grounds for the most
expedient forms of data interchange.  Hopefully that will make it
easier to achieve international agreements on topics not yet covered
by the FITS WCS papers and permit recommendations for improvements and
restrictions in the existing WCS usage.

--
Steve Allen          UCO/Lick Observatory       Santa Cruz, CA 95064
sla at ucolick.org      Voice: +1 831 459 3046     http://www.ucolick.org/~sla
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