VOTable describing image data

[DIDELON Pierre]

Hi Norman,

I am not sure to understand very well all the points and  
implication of your mail, but it gives rise to the following
comments comparing HDX and a possible VOTable extension,
only as food for thought.

First of all, VOtable has been accepted (more or less easly)
by the whole VO community. Extending VOTable (to a kind of
VOData or whatever could be the name even VOTable V2.0)
to handle any kind of data seems very easy and quite 
straightforward. So, it will perhaps be easier to adopted by 
the VO community than to introduce an other kind of format.

2nd VOTable has a complex structure with several level of
metadata (VOTable/resource/table) and recursivity (resource)
which allows a great flexibility which seems not to be available
in HDX (as far as I understand the doc available, starting with
http://www.astro.gla.ac.uk/users/norman/star/java/hdx/hdx-overview.html),
and so seems more appropriate as a generic container devoted
to metadata handling.

3d VOTable contains now a "normalized" semantics considering
the UCD, and it is not the easiest part of the design as 
the lastest discussions illustrate it.

4th VOTable seems (at least to me) more generic and less typed
than HDX, xml tag in VOTable are more structural than semantic.

So, rather than introducing an other data format in VO, I think that 
it would be better (and easiest) to introduce missing "things" in 
the already existing VOTable format. Your experience with HDX
is certainly greatly valuable and helpfull in trying to incorporate
in VOTable what you learn is necessary for generic data handling.

Cordially,
Pierre
DIDELON
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