UCDs, metadata and AstroOntology

[Tony Linde]

There have been a few papers on the AstroGrid wiki recently arguing for
some changes to the structure and composition of UCDs. This was
discussed at an AVO Interoperability meeting in Strasbourg where the
ideas were well received.

(
For the non-astronomers, UCDs are Unified Column Descriptors, used by
CDS to 'rename' columns in astronomical tables to a standard naming
scheme - check out:
   http://vizier.u-strasbg.fr/UCD/
)

Guy Rixon first argued for splitting the UCDs into 'atoms':
  http://wiki.astrogrid.org/bin/view/Astrogrid/RefactoringUCDs
followed by a suggestion of some atom names:
  http://wiki.astrogrid.org/bin/view/Astrogrid/UCDAtomsPreliminaryList
and Anita Richards followed suit with a slightly alternative approach to
the naming of atoms:
  http://wiki.astrogrid.org/bin/view/Astrogrid/WhatAreUCDsFor

Not to be left out, I've jumped in with:
  http://wiki.astrogrid.org/bin/view/Astrogrid/AreUCDsMetadata
arguing that some of these atomic combinations are embedding metadata
into the column names when it should be kept separate and distinct.

The reason for raising this here is that I could see the atomising of
UCDs, if CDS decide to adopt this approach, being a useful first step
towards creating an AstroOntology (not that I am in any way suggesting
that the argument *for* an AstroOntology is settled).

What do people think? Should UCD names for specific columns contain
everything to make them unique across all of astronomy or only within a
table? Will refactoring of the UCDs into atoms help in creating a final
AstroOntology?

For the non-astronomers reading this list, please contribute. Have you
come across similar problems in other fields? How were they solved?
Should column names reflect the full meaning of a column or only its
meaning within the context of the table in which it occurs? What are the
pros and cons?

Cheers,
Tony. 

__
Tony Linde                       Phone:  +44 (0)116 223 1292
AstroGrid Project Manager        Fax:    +44 (0)116 252 3311
Dept of Physics & Astronomy      Mobile: +44 (0)7753 603356
University of Leicester          Email:  tol at star.le.ac.uk
Leicester, UK   LE1 7RH          Web:    http://www.astrogrid.org