Subject: Re: binary tables discussion

From: [email-masked]
Date: Wed, 09 Dec 92 16:00:47 +0100

Garching, Dec. 9, 1992
Dear WGAS FITS Committee Members,
 I have followed the discussion in the WGAS FITS Committee concerning
the BINTABLE proposal and think it would be useful to state some
procedural points. The general procedure for accepting a proposal
as a FITS standard is summarized in the following points:
 1) General discussion to identify if a proposal is of general
    interest and reasonable to promote as a standard,
 2) Submission to the regional FITS groups for detailed discussion,
 3) Test implementation to verify that proposal is feasible and
    well defined,
 4) Motions in support of the proposal in the regional FITS groups,
 5) If all groups support the proposal, it is submitted to the IAU
    FITS WG for final review,
 6) Full test and demonstration of transport of data between different
    sites and systems,
 7) Final vote in the IAU FITS WG,
 8) Proposal by IAU FITS WG to IAU General Assembly to recommend the
    proposal as a standard.
The three new FITS proposals are currently at point 4 where the
European FITS Committee already this summer has passed a motion in
support of them.
 In case the three regional FITS groups (WGAS, Japanize, European)
cannot reach agreement on a proposal, it would not be passed on to
the IAU FITS WG. To resolve the current problem with character string
in BINTABLE's I suggest that the WGAS FITS Committee try to find its
own consensus on the matter. If that consensus is different from the
proposal, the Chairman of WFC should inform the Chairman of the IAU
FITS WG. He would then report it to the Chairmen of the other regional
FITS groups with a request to consider supporting the new proposal with
motions.
 The discussion under point 1 (through sci.astro.fits) should normally
avoid that an official iteration of proposals is made between the
different FITS groups. Although there was a discussion on the character
string issue in the spring it was obviously not detailed enough. To
avoid delays, I will already now ask the other FITS groups whether or
not they would have any objections in including arrays of strings by
allowing TFORM = 'wAn' formats.
 The issue was discussed in during the European FITS Committee meeting
in May 1992.  It was not considered so important that the proposal
should be rejected and a revision made.  The main argument was that
one later could add a convention which would interpret 'wA' formats
as 'wA1' and allow 'wAn' formats. Files written with 'wA' would then
still conform.
 Personaly, I would support arrays of strings with the 'wAn' format.
It would give a more symmetric definition compared to ASCII tables
which include strings as a basic type. Further, it would solve some
problems if we later would like to save definitions of multi-dimensional
array in single columns e.g. corresponding to CUNIT and CTYPE.
 I believe it is reasonable to have this issue resolved before a vote
is made and suggest that the WFC try to reach a consensus possibly
through a revision of the proposal. Although the IAU FITS WG may make
clarifications and minor revisions of a proposal during its review, it
should not change basic issues like data types or formats allowed.

Best regards,

Preben Grosbol, ESO
Chair, IAU FITS WG,
Chair, European FITS Committee.