content, format, ctype, or xtype ?

[Mark Taylor]

As far as I'm concerned, Paul's/Francois's idea of encoding this 
representation type information in the UCD would be an acceptable 
solution if the details can be sorted out.  But we'd better check 
with the Semantics WG before asserting that nobody's elegant visions 
are being compromised.

On Wed, 13 May 2009, Doug Tody wrote:

> Seriously though, using UCD would seem to provide a simple solution
> without violating anyone's elegant vision and without compromising
> UTYPE or UNIT which have more precise usage.  Something simple like
> time, time.iso8601, time.mjd, pos.stc might suffice, and the scheme
> is easily extensible.
> 
> 	- Doug
> 
> 
> > Paul Harrison wrote:
> > > 
> > > On 2009-05 -13, at 19:24, Patrick Dowler wrote:
> > > 
> > > > So.... UCD?
> > > > 
> > > > It looks like I object to everything but ucd: it allows one to say
> > > > "this is a time". Maybe restriction is enough:
> > > > 
> > > > MJD: DOUBLE <-> datatype="double" ucd="time"
> > > > ISO8601: TIMESTAMP <-> datatype="char" ucd="time"
> > > > STC-S: REGION or POINT <-> datatype="char" ucd="pos" ?
> > > > 
> > > > Specifically for upload to a TAP service, if the ucd attribute was
> > > > missing, the service would put the timstamp values into a VARCHAR
> > > > column instead of a TIMESTAMP column. Some things might still work.
> > > > If someone replies that there is a suitable UCD fragment for
> > > > position (pos?) and energy (?) then maybe we just have to spell this
> > > > out (specifically, the table in TAP 0.42, page 19 would be changed
> > > > from VOTable:format to VOTable:ucd and we would specify UCD
> > > > fragments that signify the content).
> > > > 
> > > > PS-when I say ucd="time" I really mean the ucd attribute contains a
> > > > "time" fragment. Can we make this precise enough?
> > > > 
> > > 
> > > I don't think that this covers all the bases, as there is also the POS
> > > expressed as sexagesimal - but running with this idea, what about a
> > > set of secondary UCD words format.MJD, format. ISO8601, format.STC,
> > > format.hms, format.dms to be added to time.epoch etc.
> > > 
> > > 
> > > Paul

-- 
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/