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proposal for valence items



	A few weeks ago I proposed a group of items related to the
reporting of bond valences.  There has been no comment on this proposal,
but my email did produce two suggestions for additional items - one a
rewording of a definition related to absolute structure and absolute
configuration proposed by Howard Flack and a suggestion from Gotzon
Madariaga that we should have some terms defining twins.  Gotzon declared
himself unqualified to make a proposal regarding twinning and the subject
is sufficiently complex that we need a group of twin experts to come up
with the appropriate dictionary definitions.  This could take quite a bit
of time.  Does anyone have suggestions as to good people to approach for
this topic?

	I have incorporated Howard's new definition into my valence
proposal but the wording of these two proposals remains as it was when the
proposals were presented to the discussion list.  I would now like to move
these proposals forward to Comcifs.  There they will be reviewed by the
Dictionary Review Committee and then be presented to Comcifs for a formal
vote of approval.  I can provide a copy of the complete proposal if any
one wants.

	There are likely to be other items coming to the Core DMG in the
foreseable future.  The proposed electron density dictionary includes the
definition of a local axis system around individual atoms which may well
have applications elsewhere.  The magCIF dictionary may also have some
items that would be appropriate for the core.  However, I think it is best
to deal with each of these proposals as they come forward, rather than
waiting until we have a large group of items to present.

	I would ask members of the coreDMG to let me have your approval of
the valence and absolute structure items in the next few weeks.  If
I hear nothing from you by Dec 1 I will assume that you are in favour but
it is always more encouraging to get a message to let me know that
you are still alive and reading your email.

			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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