content, format, ctype, or xtype ?

[Arnold Rots]

MJD is NOT a format!

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
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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/
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