[fitsbits] FITS 'P' descriptors: signed or unsigned?

[Francois Ochsenbein]

Yes for the 64-bit in BITPIX / K / Q, but I would stronly suggest to 
*NOT* expand the pointer/length from 31 to 32 bits in the P convention:
first the gain is minimal, and second the limit on file size of 32-bit
Unix machines used to be 2Gb, and not 4Gb -- the "largefile" Unix 
extension was a move beyond 2Gb, and not beyond 4Gb (the 'G' here
means 1024^3)

There was also some suggestion about having a versioning mechanism in
FITS -- and it would be a great benefit, I think, to know right from the 
beginning of a FITS input stream that it has (or may have), far beyond the 
beginning of the file, some extensions which may NOT be recognized by an 
old software. I feel this modification would be a good opportunity to
include this versioning mechanism in FITS.

--Francois.
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Francois Ochsenbein       ------       Observatoire Astronomique de Strasbourg
   11, rue de l'Universite F-67000 STRASBOURG       Phone: +33-(0)390 24 24 29
Email: francois at astro.u-strasbg.fr   (France)         Fax: +33-(0)390 24 24 17
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