Vocabulary: http://www.ivoa.net/rdf/datalink/core
Author: Markus Demleitner <msdemlei@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".