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[fitsbits] Start of the CONTINUE keyword Public Comment Period



 
 
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  #1  
Old July 12th 07, 05:40 PM posted to sci.astro.fits
Rob Seaman
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Posts: 49
Default [fitsbits] Start of the CONTINUE keyword Public Comment Period

The CONTINUE convention, however, is different in providing a more
general capability that could be used, for instance, within any
other convention.


I don't think I emphasized this point enough. A continuation
convention, whether the one on the table or any other, changes the
meaning of other conventions. One could, for instance, recast a
CHECKSUM keyword:

CHECKSUM= 'nADTnADQnADQnADQ' / ASCII 1's complement checksum

as:

CHECKSUM= 'nADTnADQ& ' / ASCII 1's complement checksum
CONTINUE 'nADQnADQ'

This would apply to your favorite string valued keyword as well. The
example above would be a legal continuation but an illegal checksum
value. (More than illegal for this example since the byte ordering
needs to be preserved for the zeroing feature of the checksum to work.)

Perhaps we need a broader discussion of the boundaries of usage for
conventions. I suspect the issue of long values for string keywords
remains an issue for the trusty old standards process, not the avant
garde registry. Continuation is only one possible way to handle long
strings.

Rob


  #2  
Old July 15th 07, 02:46 AM posted to sci.astro.fits
Craig Markwardt
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Posts: 232
Default [fitsbits] Start of the CONTINUE keyword Public Comment Period


Rob Seaman writes:
The CONTINUE convention, however, is different in providing a more
general capability that could be used, for instance, within any
other convention.


I don't think I emphasized this point enough. A continuation
convention, whether the one on the table or any other, changes the
meaning of other conventions. One could, for instance, recast a
CHECKSUM keyword:

CHECKSUM= 'nADTnADQnADQnADQ' / ASCII 1's complement checksum

as:

CHECKSUM= 'nADTnADQ& ' / ASCII 1's complement checksum
CONTINUE 'nADQnADQ'

This would apply to your favorite string valued keyword as well. The
example above would be a legal continuation but an illegal checksum
value. (More than illegal for this example since the byte ordering
needs to be preserved for the zeroing feature of the checksum to work.)


Bill, could the convention be clarified to indicate that CONTINUE
should not be used for keyword values that could fit in a single FITS
card? And/or, that CONTINUE should be avoided for standard FITS
keywords?

Craig

 




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