content, format, ctype, or xtype ?

[Doug Tody]

I think these have been two different discussions: one was how to
specify coordinate frame information in the TAP_SCHEMA (this is not
a votable specific issue), and the other was the problem I think we
are discussing here, which was the more general problem of how to
identify the representation used for an item in an arbitrary votable
field/param.  But the discussion we are having illustrates my point
that perhaps we don't yet understand well enough what problem we are
trying to solve.

 	- Doug


On Mon, 4 May 2009, Arnold Rots wrote:

> I'm not sure I understand the present discussion.
> I think it is about the coordinate metadata of columns in a VOTable.
> But I was under the distinct impression that we had solved that
> through a compromising process to attach those metadata by means of
> utypes. So, I would have expecetd these columns to be complemented by
> such utypes, to provide a complete desciption.
> However, this discussion sounds like designing a different
> mechanism. Why complicate matters by doing the same thing in two
> different ways?
>
>  - Arnold
>
> Francois Ochsenbein wrote:
>>
>> Yes it has to do with a semantic content of the field, but
>> the 'utype' that I tried to propose several times does not
>> seem to be satisfactory to TAP . There are 2 cases currently
>> "iso8601" and "stc-s" to specify time stamps and STC expression.
>>
>> Personnally I still would prefer the 'utype' which has the
>> advantage of being more accurate in its definition, and is
>> versionable...
>>
>> -- Francois
>>
>>>
>>> Hi Francois -
>>>
>>> It would help to have a list of common "data representations" which
>>> we are trying to characterize with this attribute.  I originally
>>> thought it was the numerical format, but it now sounds like it may be a
>>> broader concept having to do with the semantic content of the field.
>>> If we just list all the currently forseen values, perhaps we can
>>> identify the concept.  What is "x"?.
>>>
>>> 	- Doug
>>>
>>>
>>> On Sun, 3 May 2009, Francois Ochsenbein wrote:
>>>
>>>>
>>>> Hi Pat, Mark, Doug,
>>>>
>>>> I would like to come to a final wording for the new attribute
>>>> in VOTable which would specify the data representation of
>>>> columns having a special meaning like STC-S or time. None of
>>>> the various propositions (encoding, format, content, ctype)
>>>> got real support; it seems that 'content' was felt as a
>>>> bit more acceptable than the other terms. A last proposal
>>>> could be 'xtype' (some condensed way of "expression type")
>>>> would that be acceptable for tap ?
>>>>
>>>> See you soon,
>>>> Francois
>>>>
>>
>> =======================================================================
>> Francois Ochsenbein    ------   Observatoire Astronomique de Strasbourg
>>    11, rue de l'Universite 67000 STRASBOURG  Phone: +33-(0)390 24 24 29
>> Email: francois at astro.u-strasbg.fr (France)    Fax: +33-(0)390 24 24 17
>> =======================================================================
>>
> --------------------------------------------------------------------------
> Arnold H. Rots                                Chandra X-ray Science Center
> Smithsonian Astrophysical Observatory                tel:  +1 617 496 7701
> 60 Garden Street, MS 67                              fax:  +1 617 495 7356
> Cambridge, MA 02138                             arots at head.cfa.harvard.edu
> USA                                     http://hea-www.harvard.edu/~arots/
> --------------------------------------------------------------------------
>