Subject: ORIGIN and CREATOR keywords

From: "Clive Page, Leicester University, UK" <CGP at STARLINK.LEICESTER.AC.UK>
Date: Tue, 26 Oct 93 9:57 GMT

The problem with the original FITS definition of ORIGIN as "the
organization creating the FITS file" is that it's quite hard to write
software to define it correctly.  It is easy enough, and obviously
sensible, to encode in a FITS file the program name and version number
that produced it. It isn't too hard to pick up the user-name of the
person running the program through the appropriate system call, but it
is not as easy to obtain the name of his/her organization.  Some
programs that I write end up being used in a number of other
organizations - if I were to hard-code the name of my organization then
that would obviously be misleading much of the time.  An alternative
would be to force the user to enter a suitable string every time the
program is run - but users are not going to understand why they have to
do this. A third possibility is to require that the software be
"installed" so that a suitable logical name or environment variable can
be defined at install-time and picked up at run-time.  None of these
strikes me as very attractive. 

In practice, therefore, the ORIGIN keyword doesn't often get used for
its original purpose.  I don't see this as terribly serious: maybe we
should abandon ORIGIN if it isn't easy to use or all that important. I
think "CREATOR" sounds like a good name for the information that really
does need to be included in each FITS file. 

- Clive Page

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From: arots at xebec.gsfc.nasa.gov (Arnold Rots)
Date: Tue, 26 Oct 93 08:42:15 EDT

> does need to be included in each FITS file.

In reaching this conclusion he points out that it is often difficult for
software to figure out which organization is running it.  One of the
reasons this issue came up, though, is that there are situations where
the use of ORIGIN according to its original intent *is* quite meaningful.
This is especially true for FITS files that contain raw observational
data or calibration information.  The software that generates these files
usually runs at a limited number of institutions and is not exported by
users, so special provisions to ensure a correct ORIGIN  do not pose a
severe restriction.

Since there is this legitimate, albeit somewhat limited, use of ORIGIN
in its original meaning, we are proposing the introduction of this new
keyword, CREATOR, to fulfill the role that people have sometimes given
to ORIGIN (i.e., a program name) in situations where an institution's
name did not make a whole lot of sense.

  - Arnold Rots

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From: thompson at serts.gsfc.nasa.gov (William Thompson)
Date: 27 Oct 93 01:27:48 GMT

"Clive Page, Leicester University, UK" <CGP at STARLINK.LEICESTER.AC.UK> writes:

>that would obviously be misleading much of the time.  ...

	(rest deleted)

Of course, the same could be said about the keywords TELESCOP and INSTRUME,
which in my opinion are critically important.  It can also be important, from a
data management point of view, to know which of several co-investigator
institutions processed a specific file.

I use IDL to process data, but it wouldn't tell you much to say that IDL wrote
a FITS file.  It would mean more to tell one that it was written by the CDS
data processing software, because that would mean that certain specific steps
were taken in processing the data.

Bill Thompson