[fitsbits] Start of the CONTINUE keyword Public Comment Period

[William Thompson]

I'd like to make a couple of points about the CONTINUE convention.

First, I recommend that wording be added to disallow the usage of the convention 
for any keyword relating to the physical organization of data within a FITS 
file.  For example, one should not be able to continue keywords such as 
"TDIMnnn" or "EXTNAME".

Second, I'd like to make some comments about keyword ordering.  In solar physics 
it's common to convert FITS headers into structures upon reading.  For example, 
the simple FITS header

SIMPLE  =                    T /Written by IDL:  Fri Jul 13 15:52:15 2007
BITPIX  =                  -32 /Real*4 (floating point)
NAXIS   =                    2 /
NAXIS1  =                  100 /
NAXIS2  =                  100 /
END

would be converted into a structure with tag elements

    SIMPLE          INT              1
    BITPIX          LONG               -32
    NAXIS           LONG                 2
    NAXIS1          LONG               100
    NAXIS2          LONG               100

In many cases, the arrangement of the structure is predetermined, and the FITS 
header is mined to extract the keywords corresponding to the desired parameters. 
  In such cases, the original order of the keywords within the header is lost.

I would envision that continuation lines would best be handled by the FITS 
reader, so that the resulting structure tag value would be the complete string. 
  In that case, the question of the original ordering of the keyword would be 
moot.  However, I doubt that any software would actually be changed to implement 
this until there was a real need for it.

Bill Thompson