[TAP] data type for column metadata

[Francois Ochsenbein]

Well, that's typically why the utype attribute was introduced:
specify as accurately as possible what is the meaning of a parameter
vs a data model. For instance, an ISO time could be defined as
utype='stc:AstroCoords.Time.TimeInstant.ISOTime'
the stc prefix referring tp Space-Time coordinates
(there should therefore be at the top of the VOTable
a reference to the XML schema as:
  xmlns:stc="http://www.ivoa.net/xml/STC/stc-v1.30.xsd" )

Or do you think that this is not appropriate ?
Sure it looks complex, but Arnold would answer that
specifying accurately which time is used is complex...

Cheers, francois

>
>On 2009-03-19 13:26:41 Mark Taylor wrote:
>> I believe the best way to handle this would be to introduce an
>> additional attribute on VOTable FIELDs (columns) called something
>> like "format".  The interpretation of the content of this field
>> need not (and probably should not) be specified by the VOTable
>> standard itself, but by VOTable 'customers', for instance the TAP
>> standard, or user communities.  A string column labelled
>> format="iso8601" (or possibly something like format="tap:iso8601",
>> or indeed, format="postgresql:MAC") could be processed as a string
>> by generic VOTable libraries without requiring any changes to the
>> VOTable standard or implementations, but an application which
>> understood this format type could do something sensible with it
>> as appropriate.
>
>I like this idea as it lets you specify the way something was encoded, 
>typically into a string. In TAP we could use that for timestamps and STC 
>regions (format="STC/S"?)... maybe some other uses that have not come to 
>light yet. 
>
>> Having these conventions outside the VOTable standard itself means
>> that the VOTable standard does not have to keep undergoing
>> changes as different user communities find that the type they need
>> is not currently offered by VOTable.  This benefits the VOTable
>> standard (more stable) and the user communities (less effort
>> adapting it to their uses).
>
>On a  practical level, can we feasibly request/expect such an addition to 
>VOTable (it appears that 1.2 is still a WD) and have TAP require that new 
>version of VOTable (for output)? On a relatively short timescale? 
>
>-- 
>
>Patrick Dowler
>Tel/Tél: (250) 363-0044
>Canadian Astronomy Data Centre
>National Research Council Canada
>5071 West Saanich Road
>Victoria, BC V9E 2M7
>
>Centre canadien de donnees astronomiques
>Conseil national de recherches Canada
>5071, chemin West Saanich
>Victoria (C.-B.) V9E 2M7
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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
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