[fitsmime] FITS MIME Considerations

[Steve Allen]

On Wed 2002-12-11T18:47:31 +0100, Lucio Chiappetti hath writ:
> > Note that the file extension (.fits) indicated by the MIME type
> > registration is taken to be advisory, not prescriptive.  Nothing
>
> You mean what is in the RFC is advisory, don't you ? But once it makes
> its way to the mime.types or mailcap becomes prescriptive for the server
> or the browser !

Sorry, I was being very precise.  Technically the RFC is required
because the MIME types are top-level, but aside from that the only
purpose it serves is as a wrapper.  The important contents are the
IANA registrations for the individual media types.

> I believe we should be careful. I presume that if a server (via mime.types
> or magic) can identify a ".xyz" file and issue an http header with a
> Content-Type of application/fits-whatever, the browser will obey the
> Content_Type irrespective of the file extension announced. Is this true ?

Yes, this is prescribed in RFC 2616 (HTTP 1.1), section 7.2.1.

> We should allow the (few) server administrators the maximum freedom to
> associate files with MIME types (specially if there will be many for FITS
> variations). At the same time we should prevent the default mailcap of the
> (greater number of ) browsers to override the choice of the
> administrators.

It is my impression that the media type registrations definitely
should claim the namespace for the file extension ".fits", but that
they should also include disclaiming text.  The beauty of the
IETF/IANA processes is that they are nearly free form and admit a lot
of commentary.  Perhaps something more like this:

   File extension(s): fits

   This file extension should not be interpreted as a prescription.

   The FITS standard originated in the era when files were stored and
   exchanged via magnetic tape; it does not prescribe any nomenclature
   for files on disk.
   Various sites within the FITS community have long-established
   practices where files are presumed to be FITS by context.
   File extensions used at such sites commonly indicate content
   of the file instead of the data format.

   In the absence of other information it is reasonably safe to
   presume that a file name ending in ".fits" is intended to be a FITS
   file.  Nevertheless, there are other commonly used extensions;
   e.g., ".fit", ".fts", and many others not suitable for listing in a
   media type registration.

Getting back to the timing of the effort, I am of the impression that
I should attempt to publish a new draft of the RFC, which incorporates
input from up-to-date discussions, early in the year 2003.

--
Steve Allen          UCO/Lick Observatory       Santa Cruz, CA 95064
sla at ucolick.org      Voice: +1 831 459 3046     http://www.ucolick.org/~sla
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