handling metadata with multiple values

[Arnold Rots]

Ha, but then you are not using STC correctly.
In a query you don't use the Coords type but the CoordArea type where
you would specify the area where -20 <= dec <= 90 and 0 <= ra <= 360.

So, don't do this for coordinates.  But in general, I agree that
containers are preferable.  Having plain multiple occurrences of the
same element makes me wonder whether one slipped in by mistake and
which one of the lot was really intended.

  - Arnold

Anita Richards wrote:
> 
> Ah - in the AstroGrid Registry group we came to the opposite conclusion -
> that for human maintenance of the registry entries for data sets, at
> least, it was easier for lists to be in container elements as it makes it
> much easier to see (in a properly indented document) where one
> type of element ends and the next begins.
> There are some exceptions at present for 'very important' elements with
> short lists.
> 
> However you can call the items something more informative, for example
> 
> <ucdList>
>   <ucd></ucd>
>   <ucd></ucd>
>   <ucd></ucd>
>   <ucd></ucd>
> </ucdList>
> 
> <instrumentType>
>   <instrument></instrument>
>   <instrument></instrument>
> </instrumentType>
> 
> <coordinatePair>
>   <coordinate></coordinate>
>   <coordinate></coordinate>
> </coordinatePair>
> 
> In the last example, I see that (if I understand correctly) the Space-Time
> metadata schemas from Arnold use a single type e.g.
> "coord2ValueType"
> to enter a pair of coordinates in a single element.  I can see many
> advantages to that, but not all data may have both halves of the pair
> or some queries may not care e.g. all data above dec -20 - will this be
> more complicated to impliment in a search than if (say) RA and Dec were
> separate elements?
> 
> thanks
> a
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> Dr. Anita M. S. Richards, AVO Astronomer
> MERLIN/VLBI National Facility, University of Manchester,
> Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL, U.K.
> tel +44 (0)1477 572683 (direct); 571321 (switchboard); 571618 (fax).
> 
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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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