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Re: Core CIF revisions



	Thank you all for your comments on the proposed revisions for
version 2.3 of the Core CIF dictionary.  It is great to have so much
feedback, even if it would have been more welcome earlier.  It is now too
late to deal with some of the questions raised in time for inclusion in
version 2.3 and these items will have to be held over for version 2.4
(which I hope will follow soon).

	The spate of activity in the coreDMG list has prompted some
replies to other private emails I sent out requesting information.
These will also assist in preparing for version 2.4.

	Howard Flack has made some pertinant comments, and below I explain
how I intend to deal with these, given the short deadlines.

ATOM_TYPE_SCAT
As mentioned in yesterday's email, these items are being withdrawn so that
they can be carefully thought through for list number 8.  This will be
combined with the review of multi-radiation and
multi-diffraction-experiment changes.  Howard's comments will be fully
taken into account when I prepare the dictionary copy for this revision.

REFINE_LS_EXTINCTION_METHOD
This item has also been withdrawn and left for later discussion.  While I
sympathize with Howard's feeling that this may all be junk, these
corrections are routinely applied and the reader needs to know what was
done.  It would be wrong to postpone a review of the reporting of
extinction (which is included in most archival CIFs) until someone comes
up with a better method.  We could wait a long time and in the meantime
even more junk would accumulate in the archive.

EXPTL_CRYSTAL_DENSITY_MEAS_GT etc.
These items were requested in order to transcribe information in legacy
papers and databases.  We should discourage its use in new work.  I will
modify the definition to make this clear.

EXPTL_CRYSTAL_RECRYSTALLIZATION_METHOD
I will expand the definition along the lines suggested by Howard.

CHEMICAL_PROPERTIES_PHYSICAL and _*_BIOLOGICAL
Kathleen Foreman has sent a number of examples that I will include in the
revisions to be posted after July 4.  Thank you, Kathleen.

SPACE_GROUP
Brian's corrections to the space group items were mostly related to
mistakes I made in extracting items from the symCIF dictionary.  The
symCIF dictionary is written in DDL2 and includes more items than are
proposed for inclusion in the coreCIF dictionary.  While transcription
from DDL2 to DDL1 is relatively straightforward, extracting only some of
the names left a number of references to items that are in the symCIF
dictionary, but that will not be in the Core dictionary.  Most of Brian's
comments deal with removing such references which I overlooked.

	Once again thanks for your comments which will be incorporated in
the cumulative list of revisions to be posted on July 4.

				David



*****************************************************
Dr.I.David Brown,  Professor Emeritus
Brockhouse Institute for Materials Research,
McMaster University, Hamilton, Ontario, Canada
Tel: 1-(905)-525-9140 ext 24710
Fax: 1-(905)-521-2773
idbrown@mcmaster.ca
*****************************************************



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