[iaufwg] Appendix A, END keyword

[William Pence]

Andreas,

The formal syntax in Appendix A does actually cover the case of the END 
keyword record.  Formally, the END keyword is a 
'FITS_commentary_keyword_record', and more specifically, it is the case 
where the non-blank keyword field is followed by 'anychar_but_equal'. 
In other words, since the END keyword record does not have an equal sign 
in byte 9, it is considered one of the class of commentary keywords.

It is perhaps a little odd to think of the END keyword as a commentary 
keyword, but this is the most appropriate way to classify it in this 
formal grammar.  The alternative, which I think is more undesirable, 
would be to invent a new 3rd major class of keywords just for this one 
special case (i.e., a new keyword record class that is not a 
FITS_commentary_keyword_record nor a FITS_value_keyword_record).

This also at least partially explains why the formal grammar is only 
included as an unofficial appendix to the standard rather than 
integrating it directly  into Section 4:  most FITS users would likely 
find this formal grammar rather daunting to parse, so instead, the FITS 
Standard defines  all the keyword record requirements in plain English. 
  The wording in section 4 takes precedence over the formal grammar in 
case of any ambiguities or discrepancies.

Bill

Andreas Wicenec wrote:
> - Appendix A does not define the END keyword record...
> 
> As said already, I think the document is in pretty good shape  
> already, and what I've written are just suggestions. I would agree to  
> release the document also
> without the changes, except the omission of the definition of the END  
> keyword record in appendix A.
-- 
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Dr. William Pence                       William.Pence at nasa.gov
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