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RE: The CIF BNF

  • Subject: RE: The CIF BNF
  • From: "ROBIN SHIRLEY (USER)" <R.Shirley@xxxxxxxxxxxx>
  • Date: Fri, 22 Sep 2000 14:58:40 +0100 (BST)
I agree with the spirit of this contribution, since an 80-char line 
limitation is rather arbitrary and indeed small to set in 
concrete (compared, for example with 255-chars, which is another 
possible contender).

On the other hand, I'm far from happy with it in practice.  To have 
a definite line-length limit is in many respects a considerable 
practical advantage.  If it were lifted, I hope that there would 
remain a *strongly recommended* limit of 80 chars or some other 
manageable number, to be exceeded only when strictly necessary.

Robin Shirley (now writing mainly in Pascal / Delphi / Fortran 90, so 
not personally hit by such restrictions)

------------------------------------------------------

Date:          Thu, 21 Sep 2000 14:59:35 +0100 (BST)
Reply-to:      cif-developers@iucr.org
From:          "Bollinger, John Clayton" <jobollin@indiana.edu>
To:            Multiple recipients of list <cif-developers@iucr.org>
Subject:       RE: The CIF BNF


Herbert Bernstein wrote:
> However, I also believe it is time to extend the concept of a "CIF" to
> include files with other line length limits (to be specified in the
> relevant dictionary), so that I would suggest the BNF specify the
> existence of a limit, giving 80 characters as an example, rather than
> as an intrinsic part of the definition of a CIF.  

Well, right now the 80-character limit _is_ an intrinsic part of the
definition of a CIF.  If one just modifies the BNF then the result
no longer describes a CIF -- one must first persuade COMCIFS to alter
course on the CIF specification.  My impression is that COMCIFS has
historically resisted suggestions to modify the limit.

As for the 80-character limit itself, I should like to see it lifted
entirely.  I very well appreciate that that would cause problems for
Fortran programmers trying to deal with CIFs, but that argument is like
the tail trying to wag the dog.  I also recognize that the 80-character
limit can make CIFs more readable in certain display and printing
environments, but few people are limited to such environments.  On the
other hand, the limit is completely artificial, in that it is in no way
driven by the content of the file; and it introduces unnecessary
software compatibility issues, in that the handling of violations of
the limit is not defined.  Removing the limit would make it easier to
adapt STAR parsers for CIF and vice versa.  Why retain it in any form?

Regards,

John Bollinger

--

John C. Bollinger, PhD
Indiana University
Molecular Structure Center

jobollin@indiana.edu


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