utype questions

[Roy Williams]

Fabulous job, Norman. You have crystallized many of my own unspoken 
worries. And now there is a plan for a new attribute in VOTable with yet 
another meaning.

What is the VOTable parser to do? What I do is to in the metadata to see 
if the table fits the data model I am looking for. Just like looking in 
the FITS keywords for the ones we recognize.

Here, for example, is some toy code from a VOTable application that is 
expecting a time series, and is therefoe looking for the FIELD which is 
the observation time:

    if FIELD.ucd.containsString("time.epoch")
    or 
FIELD.utype.containsString("Spectrum.Char.TimeAxis.Coverage.Location.Value")
    or FIELD.units.containsString("ISO8601")
    or FIELD.representation.containsString("STC-S"):
      print "Found FIELD with observation time"

Roy



Norman Gray wrote:
>
> Greetings, all.
>
> I am often confused about what utypes are and are for, and when I
> talk to people who claim to be less confused, they give a variety of
> very certain and confident answers, which are rarely compatible with
> each other.  These incompatibilities are not merely differences of
> opinion about syntax, but appear to represent fundamentally different
> perceptions of how utypes are scoped and designed.
>
> I've collected a number of my puzzles about utypes into a single 
> document, at
>
>     http://nxg.me.uk/note/2009/utype-questions/
>
> I don't think these are necessarily hard questions.  The problem is 
> that some of them have multiple obvious answers, which are 
> incompatible, and all of which I've heard represented as The 
> Consensus.  I don't believe this is a secure basis on which to build a 
> robust standard.
>
> I hope the questions are useful.
>
> All the best,
>
> Norman
>
>

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