VEP-005.txt

Vocabulary: http://www.ivoa.net/rdf/datalink/core
Author: François Bonnarel, Markus Demleitner, msdemlei@ari.uni-heidelberg.de
Date: 2020-06-24
Supercedes: VEP-003

New Term: coderived
Action: Addition
Label: Coderived Data
Description: Data products sharing one or more progenitors with #this.
  This could be a lightcurve for an object catalog derived from repeated
  observations, the dataset processed using a different pipeline, or the
  like.
Used-in: 
  http://dc.g-vo.org/gaia/q2/tsdl/dlmeta?ID=ivo://org.gavo.dc/~?gaia/q2/199286482883072/BP
  This is GAVO's rendition of the Gaia DR2 epoch photometry, where
  users retrieve a time series in a specific band; the time series
  in the other bands are coderived with that.

Rationale: 
  It is fairly common in complex pipelines that multiple data products
  result from a single observation.  Often, this is true even in a
  single pipeline step, and hence the data products are not in a
  progenitor-derivation relationship.  Still, researchers will want to
  know about these data products; for instance, while exploring a source
  in Gaia, a quick way to access epoch photometry or the RP/BP spectra
  is obviously valuable; such artefacts are not really progenitors of
  the catalog entry, though.  In such cases, #coderived (or perhaps one of
  its future child terms) should be used.

  Clients should offer #coderived links in a context of scientific
  exploitation of the dataset (as opposed to, say, debugging).

  The term #coderived was chosen in a longer process that included
  consideration of #sibling and #co-generated.  Both were eventually
  dropped because it was felt they could be interpreted as meaning
  "of the same kind as #this" or "produced together with #this in one
  processing step"; however, is that the common predecessor of
  #coderived and #this can be many levels up the a provenance tree.

Discussion:
  After the lively discussions on the VEPs this VEP supercedes, no
  objections were raised on this.