Comments on Canadian VO data model

[DIDELON Pierre]

About the documentation of Canadian VO Data Model - Pierre Didelon

> From: Jonathan McDowell <jcm at head-cfa.cfa.harvard.edu>
> Date: Tue, 22 Apr 2003 13:40:10 -0400 (EDT)
> To: dm at ivoa.net
> Subject: Comments on Canadian VO data model
> 
> 
> Canadian VO Data Model Comments     - Jonathan McDowell
> -------------------------------
> 
> The Canadian VO have published details of the data model used to
> describe images in their archive.
> The relevant documents are at
> http://services.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/doc/cvo/

There is a lack of an UML model (even a crude one, box & lines) 
to clarify the general design of the model and 
the top level objects/tables concerned.

The four catalog types are specialisation (certainly corresponding to
different step/level of processing) of a more general type
simply called Entry Catalog. Why distinguishing so deeply
the 4 types of catalog? SQL tables are differents, perhaps whith nothing
in common. But all these catalogs share certainly some properties
or behaviours?

> This data model is used to describe images and potentially
> spectra and other data products returned from the CVO (the voObs
> object), and also to describe entries in the derived source
> catalogs (the voSrc object which I do not review here).