[fitsbits] further reopening of Public Comment Period on the CONTINUE convention

[William Pence]

Hi Mark,

On 4/20/2016 11:21 AM, Mark Calabretta wrote:
> So it seems we now agree on creating two classes of string-valued
> keywords.  I would simply like to assign the labels "string" and "long
> string" to them.

No, I don't agree.  But in any case, you seem to be missing the main 
point that the CONTINUE convention is almost exclusively intended for 
new project-specific keywords that are not defined in the FITS standard. 
  Even if it made sense to do so, there is no mechanism in place for 
projects to declare that the new keywords that they create are of type 
"string" or type "long string".

Whether some of the string-valued keywords that are defined in the FITS 
standard are allowed to use the CONTINUE convention or not is a 
secondary issue.  In my opinion, only about 7 of the 29 (if I counted 
correctly) string-valued keywords that are currently defined in the FITS 
standard could conceivably ever have a value more than 68 character long 
(ORIGIN, AUTHOR, REFERENC, OBJECT, OBSERVER, TELESCOP, and INSTRUME). 
However, I still think it would be preferable to simply prohibit the 
CONTINUE convention from being used with any of the currently defined 
string-valued keywords.

Finally, as I described in more detail in a previous email, the next 
release of CFITSIO will support a new paradigm for reading string-valued 
keyword.  These new routines will transparently read any string keyword 
(whether it uses CONTINUE or not) and will provide an easier way for C 
and Fortran programs to read string keywords of any length. I think this 
new interface will alleviate most of the practical implementation issues 
for C and Fortran programmers that you seem to be concerned about.

regards,
Bill
-- 
____________________________________________________________________
Dr. William Pence    Astrophysicist     William.Pence at nasa.gov
NASA/GSFC Code 662     [Emeritus]       +1-301-286-4599 (voice)
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