[fitsbits] Bintable proposals

[William Pence]

As part of an ongoing effort to get a number of commonly used FITS
conventions officially incorporated into the FITS Standard document, we, the
authors of the Astronomy and Astrophysics paper that defined the format of
FITS binary tables, plan to submit the following 2 proposals to the WGAS
FITS Committee (the North American regional FITS committee) for
consideration.  As you may know, the appendices to the Bintable paper, which
describe the variable-length array convention and the TDIMn keyword
convention, were never officially approved by the various FITS committees
and are included in the FITS Standard document "for informational purposes
only".   Given that these 2 conventions have been widely used within the
FITS community for many years, we believe it is appropriate that they now be
officially endorsed.    

Does anyone have any comments on these 2 proposals before they are submitted
to the WGAS FITS committee?

Bill Pence, NASA/GSFC
Doug Tody, NOAO
Bill Cotton, NRAO


Proposal 1:
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       Recommendation to Incorporate the "Variable Length Array" 
          Facility in Binary Tables into the FITS Standard

     W.D. Pence (NASA/GSFC), D. Tody (NOAO), and W.D. Cotton (NRAO)
                           2 November 2001


The "Variable Length Array" FITS data format that is described in Appendix
B.1 of the FITS Standard is now used by a number of major data analysis
packages.  Examples of current usage include the "Redistribution Matrix
Files" (RMF), widely used in X-ray astronomy to store calibration
information about the instrumental detector gain and detector energy
resolution, and the pixel mask files used in the IRAF system.   Several
software systems provide general capabilities for reading and writing data
in this variable length array format, including the CFITSIO library
(maintained by the HEASARC at NASA Goddard Space Flight Center) and IRAF.

Appendix B.1 is not an official part of the FITS Standard and is included in
that document for informational purposes only.  We believe that the
implementations described above have now fully demonstrated the usefulness
and importance of the Variable Length Array Facility, and thus we hereby
propose that Appendix B.1  be officially approved and incorporated onto the
FITS Standard in its entirety.

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Proposal 2:
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       Recommendation to Incorporate the "Multidimensional Array" 
          Convention in Binary Tables into the FITS Standard

     W.D. Pence (NASA/GSFC), D. Tody (NOAO), and W.D. Cotton (NRAO) 
                           2 November 2001

Appendix B.2 in the FITS Standard describes a "Multidimensional array"
convention that uses the TDIMn keyword to define the dimensionality of
arrays that are contained in binary table columns.  Many FITS files now use
this convention and contain the TDIMn keyword.  Appendix B.2 is not an
official part of the FITS Standard, however, and is included in that
document for informational purposes only.  We believe that the widespread
usage of the TDIMn keyword demonstrates the usefulness and importance of the
this convention, and thus we hereby propose that the "Multidimensional
array" convention described in Appendix B.2 be officially approved and
incorporated onto the FITS Standard.
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