[TAP] data type for column metadata

[Patrick Dowler]

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
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Victoria (C.-B.) V9E 2M7