[fitsbits] 64-bit integer comments

[Thierry Forveille]

Mark Calabretta writes:
 > >I still don't see a convincing argument for adding BITPIX=64.  That it
 > 
 > The argument for maintaining consistency with 'K' TFORMs and Q array
 > descriptors seems, if not compelling, then at least persuasive.  Another
 > point is that FITS standard always seems to play catchup with what
 > people have done in practice, perhaps it should try to be proactive.
 > 
It certainly seems easy enough to add the support, but "because we can"
does not really feel like a good enough reason by itself. The only 
possibility of use that I have seen is William's mention of "only
moderately contrived examples", which does not quite match my standard.
If it's available somebody will use it for no good reason, and then
every generic reader around will be pushed towards supporting it
against their will.

Unless somebody comes up with a project that will fly within 5 years
and that needs 64 bits of dynamics in images, what's wrong with just
waiting until some actual need occurs?