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Re: [ddlm-group] Moving forward with DDLm

For the benefit of the group. let me expand a little on James' report regarding the conversion of the CIF dictionaries.  Nick and Syd converted the CIF1 core dictionary into half a dozen DDLm compliant subdictionaries to create a proof-of-principle system.  Under DDLm any number of subdictionaries can be merged into a single working dictinary.  I have been checking these dictionaries to convert them to something that COMCIFS can approve.  This includes, for example, aliasing CIF1 and CIF2 data names for backward compatibility, although for the most part the new names are the same as the old.  I have also been checking the defnitions and checking that new items work the way they are supposed to.  So far I have finished two of these subdictionaries and I am working on the third.  Learning how DDLm works also takes time.  I am passing on the resulting files to James who is preparing a validating program for DDLm compliant CIF dictionaries.  When this is working there will no doubt be more changes needed.

There are many opportunities for enriching these dictionaries by adding further methods, and some of these will require decisions by COMCIFS, but for now the priority is to get some dictionaries working so that we can locate unexpected glitches and condsider possible extensions.  In order to speed up the testing of these dictionaries I am keeping my changes to a minimum.

I agree with Herbert that the product will not be perfect, but now ia a propitious time for COMCIFS approval of a stable version of DDLm and dREL that we can change and adapt later.


James Hester wrote:
Dear DDLm group,

Now that the CIF2 syntax specification is well on the way to approval,
our energies can be turned towards the remaining pieces in the puzzle,
which are DDLm and dREL.

DDLm and dREL are the result of at least a decade of development and
consultation. Given the lack of objections to the DDLm specification
within this group, I am satisfied that the draft of DDLm that is
currently posted is sufficiently well-developed to serve as a version
0.99 document that can be accepted by COMCIFS under its normal
dictionary acceptance procedure.   This group would then become the
DDLm dictionary maintenance group (subject to formal COMCIFS
approval).  Meanwhile, work needs to be done to produce DDLm versions
of current DDL1 and DDL2 dictionaries; this may expose some minor
flaws in the DDLm specification which I believe can be dealt with as
DDLm updates.  Once a few such DDLm dictionaries are ready, we should
then be ready to release a 1.0 DDLm specification together with
accompanying dictionaries.  I note here that David Brown has already
prepared a draft Core dictionary in DDLm based on Nick and Syd's

Therefore, please indicate if you agree to submit DDLm and dREL to
COMCIFS for approval without further discussion on this list.  In any
case, if no objections are received by the end of the year (the expiry
of the term for objections to the CIF2 specification) I will submit
both DDLm and dREL to COMCIFS for approval in the New Year.


fn:I.David Brown
org:McMaster University;Brockhouse Institute for Materials Research
adr:;;King St. W;Hamilton;Ontario;L8S 4M1;Canada
title:Professor Emeritus
tel;work:+905 525 9140 x 24710
tel;fax:+905 521 2773

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