Re: MODEL guidance please

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• Previous message: Eldon Ulrich: "Re: MODEL guidance please"

I am sorry my question was misunderstood.  I am not proposing the
example I gave as a real structure, but as a thought-experiment to
discover how to structure all present levels of conformational
variantions without conflict or confusion.  If the recommended
mmCIF approach for multiple models is to use one data block per
model, then that should be clearly stated somewhere.  If the
recommended approach is to make some use of various tokens
within a single data block to allow for inter-relationships
among models to be shown, then that should be clearly stated
somewhere.  Similarly the  recommended approach to
microheterogeneity should be clearly stated somewhere.  Since
the dictionary does make rather strong statements about
occupancies, the interaction of those statements with multiple
models and microheterogenity should be stated somewhere.
Certainly it will be rare to have a single structure with
all three levels of conformational variation, but it would
be unfortunate if a dictionary-conforming structure presenting
one of the levels of conformational variation could be confused
with one presenting one of the other levels.  We can be certain
such confusion will not occur by performing the thought experiment
suggested.

Since it has been asserted that the issues involved on all three
levels _can_ be handled adequately with the present dictionary
structure, but the proposed method has not yet been explained,
I would think the request for guidance not unreasonable, and
I suggest the thought-experiment as a valid probe of the
viability of whatever approach is taken.

P.S.  The handling of occupancy in an nmr structure is an interesting
issue, especially since the NMR studies often use occupancy fields
for other quantities, but I think that issue can be put aside for
resolution by the NMR community.  What I am pointing out is a
conflict between the present wording of the dictionary and any approaches
which attempt to provide more than one model in a data block.

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