[fitsbits] start of Public Comment Period on blank header space convention

[William Pence]

I hope that preconceived notions about what does or does not belong in a 
standards document do not prevent us from including information that 
could be of real benefit to the FITS community.  A number of posts here 
have suggested that the description of a convention is for some reason 
not worthy of being in the FITS standard, but I disagree.  As a case in 
point, I think the fact that most software developers are not aware of 
the header space convention for preallocating space for more header 
keywords has been a direct contributor to the perception that FITS is 
not a very efficient format for data analysis.   Users certainly notice, 
and complain, when they are analyzing a very large file and suddenly the 
software seems to hang for a couple minutes, and the hard disk can be 
seen thrashing away,  just because Gbytes of data in the file have to be 
shifted downward in the file by 2880 bytes to make room for another 
header keyword.  This perceived inefficiency of the FITS format was even 
highlighted in the recent paper by Thomas et al. as a justification for 
their argument that FITS needs to be replaced with something new.   But 
this is not a problem with the FITS format itself, and instead the 
problem is caused by the fact that our software developer community is 
for the most part unaware of this useful convention for efficiently 
processing large FITS files.

In short, I hope we can lighten up a bit and not be quite so vigilant 
about restricting the standard to be only a dry recitation of the legal 
structure of a FITS file.  I don't think it is a sin to also include the 
occasional usage tip or example to clarify a particular topic.

/end{rant}

-Bill