VODataService becoming WD, then PR

[Mark Taylor]

On Thu, 20 Nov 2008, Roy Williams wrote:

> Pat
>> An obvious example is that ADQL makes it possible to have columns of
>> type "region" and return them in a select. The TAP spec will have to say 
>> that  the VOTable FIELD will be datatype="char" and arraysize-"*" and the 
>> content will be encoded (STC/S encoding) as a string. I do not know off 
>> hand if the FIELD allows one to say that the value is encoded; if not, then 
>> specs will likely have to chose a single encoding. 
> I have been using UCD and UTYPE for this kind of recognition in the Vim 
> application, the idea that some strings are treated specially. While making 
> HTML presentation, for example, if there is a table column whose UCD is 
> "meta.link.url", then it is rendered as a link <a href=...>, and if it is 
> "meta.link.url;obs.image.jpeg", then it is rendered as an image <img 
> src=...>. This works with other types of "special" strings that need 
> interpretation, such as region defintions. I suppose it could all be 
> rigorized with UTYPE at some point in the future.

this can be done, and since it's the only straightforward way of
associating some custom metadata with columns, the ucd, utype and units
attributes do get used for this sort of thing sometimes (including by me).
But it is essentially abuse of those attributes, since the encoding 
type is really orthogonal to the semantics of the data contained.

Mark

-- 
Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
m.b.taylor at bris.ac.uk +44-117-928-8776 http://www.star.bris.ac.uk/~mbt/