[fitsbits] Blank strings in FITS keywords.

[William Thompson]

Thomas McGlynn wrote:

> The problem is that since the first FITS paper (and still in the standard),
> the fixed format is recommended for header cards.  In the fixed format 
> there
> must be at least 8 characters in a character value.  Reading that paper
> if I wished to specify a string with the value of '' in the fixed format
> I believe I would have written it as
>    ABCDEFGH= '      '
> and felt that I was following the recommendations of the standard.

I second this statement.  In fact, the FITS-writing software that I use enforces 
the fixed format, so that it would be impossible to write a null string separate 
from a blank string, e.g.

IDL> fxhmake,h
IDL> fxaddpar,h,'abcdefg',''
IDL> hprint,h
SIMPLE  =                    T /Written by IDL:  Tue Mar  1 11:10:43 2005
BITPIX  =                    8 /
NAXIS   =                    0 /
ABCDEFG = '        '           /
END

William Thompson