UCDs, metadata and AstroOntology

[Anita Richards]

> 
> > ... As I understand it, the UCDs _are_ the meta data 
> > for each column but they are dynamic, ie built up out of 
> > atoms from the column or the header or possibly higher levels 
> > depending on the query.
> 
> I'm not sure I understand what you mean by them being dynamic. Once a
> UCD is assigned to a column, it is fixed, n'est-ce pas?

I was using 'UCD' to mean metadata built up out of atoms, and I ws
thinking that if some of the metadata is in the header and some is
identifiying column labels then the relevant UCD for a particular search
might contain more or less atoms strung together.  But, yes, the
individual atoms have to be fixed I hope!

......
> 
> As you said above, UCDs are metadata, not column names, so why not use
> the column names as the column names and store the metadata separately
> in a form that makes it easy to access and use.

Because the original column names are often very obscure?  Or are we at
cross purposes, is Tony assuming that we have already replaced every
original column label that says 'brightness' or 'Mags' or ??? with one
saying 'PHOT"? etc?  
If we agree that each column needs a metadata description then where else
do we store it?

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
Dr. Anita M. S. Richards, AVO Astronomer
MERLIN/VLBI National Facility, University of Manchester, 
Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL, U.K.           
tel +44 (0)1477 572683 (direct); 571321 (switchboard); 571618 (fax).