[fitsbits] Start of the FITS 64-bit Integer "Public Comment Period"

[William Pence]

ANNOUNCEMENT:   Start of the Public Comment Period on the
                       FITS 64-bit Integer proposal

This is to announce the official start of the 4-week formal Public Comment 
Period on the proposal to add support for 64-bit integers to the FITS data 
format.

A detailed description of this proposal is available at 
http://fits.gsfc.nasa.gov/fits_64bit.html.  This proposal would basically 
introduce 3 changes to FITS:

     1. Primary arrays or IMAGE extensions containing 64-bit integer
        data type images would be designated by BITPIX = 64

     2. Columns in FITS binary tables that contain 64-bit integers
        would be designated by TFORMn = 'nK'

     3. Array descriptor columns in FITS binary tables with 64-bit
        integer array length and heap offset values would be designated
        by TFORM = '1Qt' (analogous to the existing 32-bit descriptor
        type designated by TFORM = '1Pt').

An archive of the previous informal discussions about this proposal is 
available at http://listmgr.cv.nrao.edu/pipermail/fitsbits/.  In particular, 
see the postings in September and October 2001, and in April and May 2005.

All interested members of the FITS community are strongly urged to submit 
comments pro or con about this proposal here on the sci.astro.fits 
newsgroup, or on the related FITSBITS moderated mail list.  Following the 
conclusion of this formal comment period, it is likely that the 4 regional 
FITS committees and the IAU FITS Working Group will then vote on whether to 
formally adopt this proposal.

Finally, it would be particularly useful to the FITS committees to get wider 
community input on the 2 issues that were raised in the recent discussions 
of this proposal:

1)  Is there sufficient reason to support 64-bit integer images in FITS (in 
addition to 64-bit integer table columns)?

2)  Should the 32-bit P heap pointers be defined as positive signed integers 
(with a 2.1 GB maximum heap size) or unsigned integers (with a 4.2 GB 
maximum heap size)?.


William Pence
Chairman, IAU FITS Working Group
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____________________________________________________________________
Dr. William Pence                          William.D.Pence at nasa.gov
NASA/GSFC Code 662         HEASARC         +1-301-286-4599 (voice)
Greenbelt MD 20771                         +1-301-286-1684 (fax)