Re: VO and ADEC identifiers

Alberto Accomazzi wrote:

>
> The identifier to be used in journals to refer to a dataset will be in
> the form:
>
> authorityID/datacollection#PrivateID
>
> where both "authorityID" and "authorityID/datacollection" have entries
> in the registry. PrivateID can be anything the authorityID has chosen
> it to be, and represents a unique identifier that has been assigned to a
> dataset within the particular data collection.
>
> For instance, MAST has a number of missions it holds data for, each with
> a set of datacollections available (see
> http://archive.stsci.edu/dataset_verifier.html). Assuming the
> authorityID of "NASA.HST" has been created for the HST mission , the
> identifiers for its datasets would look something like this:
>
> NASA.HST/STIS#O4LT010E0
> NASA.HST/ACS#J8FF03021
> NASA.HST/WFPC2#U32L0104T
> ...
>

In one sentence I would simply answer that the instrument names do not add anything to the identifiers, hence they should not be used. Instrument names are part of the metadata associated with the data nothing to do with the identifier.

In the case of ESO, the instrument name is part of the identifier, repeating it would not help clarifying things; example:

 ivoa://ESO.LASILLA/#WFI.2000-12-27T01:12:55.123.fits

One could think that the data collection is better represented by the mission than by the instrument ... It is matter of taste, one could choose:

 NASA/HST#J8FF03021
 NASA/IUE#LWP25899 Other more hierarchical examples would be:

NASA/HST/ACS#J8FF03021
NASA/HST/WFPC2/F555W#U3814G02T
NASA/HST/imaging#U3814G02T       (why not?)
NASA/HST/spectroscopy#Y0Q70101T

etc etc (btw, HST is for 15% also an ESA telescope :-)

Altogether, I would prefer, as Arnold suggests, a simpler, less miss-interpretable, less arbitrary, hence not subject to the taste of people, two-key design (plus the scheme), something like:

ivoa://NASA.ESA/HST#U3814G02T

But please, no instruments (nor filters, modes, exposure times etc) in between, they don't add to the identifier!

(Yes, regarding the scheme prefix, I would prefer 'ivoa' instead of 'vo' ).

Alberto

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