VEP-017: refframe#geo_app

[Markus Demleitner]

Dear Semantics, Apps, and DM WGs,

In our refframe vocabulary, we have a term geo_app that we have
inherited from VOTable's COOSYS/@system.  When we created the
vocabulary, nobody could quite remember what it was supposed to mean,
in particular because the "geo" part made us suspect it would have
been a frame for Earth.

At the recent Interop, JJ Kavelaars recognised what this was supposed
to mean: geocentric apparent positions.  Even though the term is
deprecated (and we will not un-deprecate it for reasons mentioned
below), we should fix the ugly label and description.  This is what
VEP-017 tries:

  Vocabulary: http://www.ivoa.net/rdf/refframe
  Author: Markus Demleitner <msdemlei at ari.uni-heidelberg.de> and J.J. Kavelaars
  Date: 2024-11-17

  New Term: geo_app
  Action: Modification
  Label: Geocentric Apparent Positions
  Description: Positions given as observed by a fictitious observer at the
	  Earth’ s centre for the equator of observation.
  Relationships: narrower than #EQUATORIAL
  Used-in: VOTable legacy

  Rationale:
  When the legacy VOTable terms were added to the refframe vocabulary
  (which was necessary to keep validity criteria when VOTable changed
  COOSYS/@system to being controlled by this vocabulary), nobody rememberd
  what geo_app might have meant.  It recently turned out that it must
  have been “Geocentric Apparent”, a frame used primarly in geodesy and
  solar system science.  It is documented to some extent in
  https://starlink.eao.hawaii.edu/docs/sun211.htx/sun211ss454.html.

  This VEP replaces label, description, and relationship for the concept.
  At this point, this is a deprecated concept, and since it is mixing
  refposition and frame ("geocentre" vs. "apparent positions at equator of
  epoch"), we quite certainly won't want anyone to use it.  We still want
  to update the concept metadata and hence ask for exemption from the
  “must be used somewhere” rule.

https://github.com/ivoa-std/VEPs/blob/d79185c3a36bf704b84fe439ba4513b8cfb5304e/VEP-017.txt

Comments?  Thoughts?  I'd say this is reasonably harmless, and so I'd
suggest to bring this to the TCG in about two weeks if nobody
protests here.

Thanks,

             Markus