[QUANTITY] Plea for pragmatism

[DIDELON Pierre]

> From owner-dm at eso.org Wed Oct 29 20:13:36 2003
> Date: Wed, 29 Oct 2003 12:07:06 -0700 (MST)
> From: Doug Tody <dtody at nrao.edu>
> To: dm at ivoa.net
> Subject: Re: [QUANTITY] Plea for pragmatism
> 
[snip]
> 
> A global, all encompassing data model for something like an imaging
> observation could be very complex.  A better approach might be to simply
> provide a mechanism to aggregate and associate the component data models
> to model actual instances of complex datasets.

I totally agree.

> 
> The hierarchy needed is something along these lines:
> 
>     Container
...
>     Component data model
...
>     Quantity
...
> 
> Our most urgent need is for the component data models, 

Could we try to make a list of components, from the common concepts listed in Strasbourg
(http://www.ivoa.net/twiki/bin/view/IVOA/InterOpOct2003DataModel)
and perhaps some items of interest evocated in Cambridge,
and then give them priorities.

I think that at the same time we could try to define the global area of DM,
even in a fuzzy manner, by defining "package" or "domains". 
IMO trying to see the relations between components and domains
will perhaps help us establishing the "landscape" and the domain borders.

> 	and simple models
> for things like image and spectrum/SED.  We also need to define ways to
> represent such data models in formats such as XML/VOTable.
> 
Francois Bonnarel (CDS) already made this exercice within VOTable.
Can he post something concerning that?

Pierre