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Westbrook's draft dictionary

• To: Multiple recipients of list <imgcif-l@bnl.gov>
• Subject: Westbrook's draft dictionary
• From: "I. David Brown" <idbrown@mcmail.CIS.McMaster.CA>
• Date: Thu, 30 Jan 1997 12:03:41 -0500 (EST)

	I had a look at John's draft dictionary.  I may be missing 
something but it seems to me that this draft presents a solution  
that we discussed earlier and rejected.

	He treats the binary file as a piece of STAR text set between
semicolon delimiters.  There are a number of difficulties with this
seemingly simple solution.  Firstly the STAR definitions requires all
fields to contain only ascii characters.  Secondly carriage returns are
used to terminate lines even within text strings without themselves being
part of the text.  Finally there is no guarantee that a binary string will
not contain the code for 'CR ;' thereby terminating the string in the
middle.  Any binary sequence cannot, in the nature of things, be
self-terminating, its length has to be specified externally, and this is
contrary to all the principles of STAR.  I would be delighted to discover
that this problem is overcome in DDL2, but it seems to me insurmountable. 
That is why we have been leaning towards a fully binary file with an
extractable ascii header that when extracted is cif compatible. 


*****************************************************
Dr.I.D.Brown
Brockhouse Institute for Materials Research, 
McMaster University, Hamilton, Ontario, Canada
1-(905)-525-9140 ext 24710
*****************************************************

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