VEP-006, definitions of datalink/core#calibration and its descendants

[Markus Demleitner]

Dear DAL, dear Semantics,

Here's another VEP on the Datalink vocabulary; since it's the oldest
vocabulary, I'm not yet unnerved by the fact that all our VEPs
concerned it so far, but given we're still in the validation phase of
Vocabularies 2.0, I'd like to once more invite further contributions,
possibly to other vocabularies, too.

This VEP is a bit of a novelty against what we had so far, in
that it proposes not new terms but changes to existing terms: We try
to narrow down the definitions so hopefully annotators will
consistently use them.

As usual, I'm grateful for any kind of feedback; even just one or two
+1-s would give me some indication that people have actually thought
about the proposal for a bit.  Some interactive discussion on this
can also take place during the next installment of Semantics Calls,
planned for early October [btw., minutes from last time are at
https://wiki.ivoa.net/twiki/bin/view/IVOA/SemanticsCalls-1].

You are also welcome to edit the VEP in Volute,
http://volute.g-vo.org/svn/trunk/projects/semantics/veps/VEP-006.txt
The text there at this point is what is reproduced below.

Thanks,

           Markus



Vocabulary: http://www.ivoa.net/rdf/datalink/core
Author: Markus Demleitner <msdemlei at ari.uni-heidelberg.de>
Date: 2020-09-09

Term: #calibration
Action: Modificiation
Description: Data products that can be used to remove instrumental
  signatures from #this.  Note that the calibration steps such data
  products feed have not been applied to #this yet.   To link
  calibration data already reflected in #this, use #progenitor.
Used-in: http://dc.g-vo.org/kapteyn/q/dl/dlmeta?ID=ivo%3A//org.gavo.dc/~%3Fkapteyn/data/fits/POT015_000317.fits

Term: #bias
Action: Modification
Description: Data products that can be used to remove detector offset levels 
  from #this.

Term: #dark
Action: Modification
Description: Data products that can be used to remove detector dark 
  current from #this.

Term: #flat
Action: Modification
Description: Data products that can be used to remove the signature of
  non-homogeneous detector sensitivity from #this.

Rationale: 
  In a discussion on the semantics mailing list (see
  http://mail.ivoa.net/pipermail/semantics/2020-June/002735.html
  and follow-ups) it was found that the existing descriptions of
  #calibration and its narrower terms are ambiguous; "resource used
  to calibrate" could mean both "resource that has been used" or
  "resource that can be used".  This VEP tries to make it clear that the
  "has been used" interpretation is for #progenitor, wheras #calibration
  is for "can be used".