[iaufwg] Final FITS review comments

[Don Wells]

Doug Tody wrote:
> ..  [Bill Pence wrote:]
>> 16.  from Mark Calabretta:
>>     
>>> The new Standard should note any inconsistencies in syntax
>>> between previous versions of the Standard, either as an
>>> appendix or as footnotes throughout the document.
>>>       
>> ..  No one seems to know of
>> any specific cases of changed syntax that should be documented,..
>> I would like to hear how other members feel about this issue..
>>     
>
> I .. cannot think of syntax
> changes although there have been other kinds of changes to FITS
> over the years..

I too am unsure whether there have been any syntax changes.   I suggest 
that members of this committee respond to this thread of discussion with 
any changes that they know about. 

The only case that raises suspicion in my mind is complex-valued 
keywords.   The original 1981 Wells&Greisen paper recommended two 
numbers delimited by one or more blanks, preferably in the fixed-format 
columns, but then it also stated that the fundamental rule is 
conformance to the rules of the Fortran-77 list-directed-read.  The 3.0b 
document specifies, as did v1.0 previously, the use of parentheses and a 
comma, and it talks about complex integer as well as complex floating 
point values. The v1.0 FITS Standard asserted that there is no fixed 
format for complex numbers, a statement which overlooked the 1981 paper 
rule.   I don't have ready access to my copy of the F77 standard, so I 
can only conjecture that the parentheses-plus-comma complex-valued 
format rule came from the F77 standard.  For some reason I had not 
noticed the slight inconsistency of rules in previous reviews of FITS 
Standard documents.

I suggest that any known syntax changes be flagged with footnotes.   I 
see no need to attempt to achieve completeness, just note any known cases.

> .. when the most recent document was put out
> for review there was a written summary of the important changes.
> The first thing we should do is preserve such information and make
> it available along with the actual specification..
>   

Agreed.

-Don
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