handling metadata with multiple values

[Anita Richards]

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).