[fitsbits] Some FITS ambiguities

[Paul Barrett]

I have three questions about version 2.0 of the FITS standard that the
NOST document doesn't appear to cover.

1) What is the recommended procedure for handling a keyword value that
is >4294967296 (i.e. a 32-bit unsigned integer), or similarly,
>18446744073709551616 (ie. a 64-bit unsigned integer)?

Note that in fixed format an integer can have 20 digits. If they are all
9s, the integer is greater than a 64-bit unsigned integer.  And in free
format, integers can have 70 digits.  How are these numbers to be
handled?  By a BCD library?

2) What is the practical difference between a null string (i.e. '') and
a blank string (i.e. '        ')?  See page 16 of the FITS standard.
They are both strings. Does it really matter if one has 8 spaces and the
other 0 spaces?

3) The FITS standard notes that a series of digits with leading zeros is
considered a decimal number, not an octal number as found in many
programming languages.  (Kind of a shame really.)  The FITS standard
does not note whether this is also true for floating point numbers.  Can
floating point values contain leading zeros?


--
Dr. Paul Barrett       Space Telescope Science Institute
Phone: 410-516-6714    DESD/DPT
FAX:   410-516-8615    Baltimore, MD 21218