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Re: New version (2.3) of core CIF dictionary available

Dear Brian

At 14:41 04/10/2003 +0100, you wrote:
>The core CIF dictionary (coreCIF) version 2.3 has been posted.
>
>Among the significant changes are the following:
>
>Two new categories, SPACE_GROUP and SPACE_GROUP_SYMOP have been introduced
>to provide more correct definitions of the crystallographic space group
>symmetry of a structure. These categories have been imported from the
>symmetry CIF dictionary, which is designed to provide data names required
>for a complete description of crystallographic symmetry. The existing
>categories SYMMETRY and SYMMETRY_EQUIV are formally marked as deprecated,
>and developers should begin the process of migrating to the new
>categories. (In accordance with the archival purpose of CIF, the old data
>names will be retained in the dictionary, but CIF reading software that
>needs to extract symmetry information should be designed to query both
>sets of possible names, either through hard-coding or by following the
>_related_items links in the dictionary.)

I have started to implement these changes in WinGX. However I find that CIF's
using these new data  names are rejected by the IUCr Checkcif service as 
invalid because
symmetry information is missing. It would be helpful if the IUCr wishes the 
community
to switch to these new names for their own checking software to recognise 
them !

At present I am unsure whether to distribute a version of WinGX using these 
new names
because many programs may be unable to read the new format CIF's. For 
instance the CCDC's
excellent programs Mercury and Encifer are unable to recognise these new names.

Best wishes Louis


=====================================================================
From:
Dr. Louis J. Farrugia
Department of Chemistry
University of Glasgow,
GLASGOW G12 8QQ
Scotland, UK.

Phone:  +44 (0)141 330 5137
FAX:    +44 (0)141 330 4888
email:  louis@chem.gla.ac.uk
Web  :  http://www.chem.gla.ac.uk/~louis/
=====================================================================


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