[fitsbits] Dataset identifications.

[Thomas McGlynn]

There is an effort underway at several of the NASA archives
to provide a standard dataset identifier for data that
can be retrieved from the archives.  The initial motivation
is that when authors publish a paper they will be able
to specify the data that was used in analysis and systems
like the ADS will be able to provide links to these data
in a systematic way from the papers (and vice versa for
the archives). Currently this is done for a few datasets
but it's a very manual and labor intensive process.  Although
the initial impetus is coming from some of the NASA sites,
we've been talking with the VO efforts and hope that the
ID will be of general utility.  I've no doubt that if ID's
become established they will be used in many
different ways.

There are discussions still ongoing as to the exact format
to be used.  It is intended that the overall format will be
compatible with the identification standards that are being
discussed in the Virtual Observatory world.  An example ID
might be ADS/Sa.ROSAT#X/rh701576n00 where the ADS indicates
the the ADS will provide the high level resolution service,
the 'Sa.ROSAT' is an observatory identifier, and the
element that follows the # is observatory specific, but
should be familiar enough for those who have used ROSAT
data.

The question for this group is not so much a discussion of the format
of the ID.  Rather it was pointed out that if these IDs are successful
it would be useful to be able to have a standard
FITS keyword that would indicate the dataset id that the current
file belongs to.  The keyword 'DS_IDENT' has been suggested.
Does anyone have objections to this or do they know of systems
that already use this keyword?  Googling DS_IDENT returns an album
of Donna Summer's but no FITS references.

Also, are there any issues the we need to resolve regarding
the usage of the keyword?  One that comes to mind is whether use of this
keyword should be recommended only for the primary header of a FITS
file.  If not then a file may not be associated with a unique dataset
id.

I'd appreciate any comments, questions or thoughts on the subject.

	Thanks,
	Tom McGlynn
	HEASARC