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Re: Variants

I include David's original message below for reference.

---------------------------
(from David Brown)
Dear Colleagues,

Last September I circulated for fast track approvel a recommendation for adding a new item:�������������������������
����

� � � � � � � �� _diffrn_radiation_wavelength_nominal,

to the core dictionary (see below for details).� The intent was that this could be used for giving a nominal wavelength calculated e.g., from the paparmeters of a diffractometer.� It was proposed tht this might be needed for completeness even though it was not accurate enough for calculating� lattice parameters, etc.� This proposal was passed by the core CIR dictionary maintenance group by default (no one raised any objection).� When this proposal was subsequently presented for final approval to COMCIFS, Nick Spadaccini suggested a more elegant alternative, namely that by adding instead the item

��� ��� _diffrn_radiation_wavelength_determination�

we could loop the nomiinal wavelength with the� refined (and any other interesting) wavelengths.� This would be more informative and allow for future expansion.

An example of how this might be used is:

�� �� �� loop_
��� �� �� �� _diffrn_radiation_wavelength_id
��� �� �� �� _diffrn_radiation_wavelength
���� ��� ��� _diffrn_radiation_wavelength_determinaton
��� �� �� �� �� 1�� 1.23456�� fundamental
��� �� �� �� �� 2�� 1.25�� �� estimated

According to our rules, this proposal is being posted for comment to the coreCIF dictionary maintenance group for the next six weeks.� At the end of this time, if there are no unresolved issues, the core dictionary maintenance group will be deemed to have accepted the proposal.

David Brown

==============================================================

The proposal is to add the following item to the coreCIF dictionary:
=============================================
2009-09-25 Proposal from the Nick Spadaccini on the COMCIFS dicsussion list to replace a withdrawn proposal.

data_diffrn_radiation_wavelength_determination
� _name � � � � � � � � � � �'_diffrn_radiation_wavelength_determination'
� _category � � � � � � � � � �diffrn_radiation_wavelength
� _type � � � � � � � � � � � �char
� _list � � � � � � � � � � � �both
� _list_reference � � � � � �'_diffrn_radiation_wavelength_id'
�loop_
� �_enumeration
� �_enumeration_detail
� 'fundamental' � � � � ��
������ 'Wavelength that is a fundamental property of matter e.g. MoK\alpha'
� 'estimated' � � � � � � ��
������ 'Estimated from secondary information e.g. monochromator angle or time of flight'
� 'refined' � � � � � � � ��
������ 'Based on refinement using a standard material with known cell parameters'


� _definition
; � � � � � � �The method of determination of incident wavelength. Further information may be provided in _diffrn_radiation_special_details
;


On Thu, Nov 26, 2009 at 1:14 PM, Herbert J. Bernstein <[email protected]> wrote:
You removed David's original message from mine. �Please add that to
the thread as well.


=====================================================
�Herbert J. Bernstein, Professor of Computer Science
� Dowling College, Kramer Science Center, KSC 121
� � � �Idle Hour Blvd, Oakdale, NY, 11769

� � � � � � � � +1-631-244-3035
� � � � � � � � [email protected]
=====================================================

On Thu, 26 Nov 2009, James Hester wrote:

I'm reposting Herbert's message in a new thread to aid organisation.�
Herbert wrote:

----
Dear Colleagues,

�While you are revisiting this item, I would suggest you consider the more
complete (and, I believe, more elegant and general) solution of defining
"variants", that we have introduced into the imgCIF dictionary to handled
quantities that may be determined in different ways.

�Instead of adding

�_diffrn_radiation_wavelength_determination

you would add

�_diffrn_radiation_wavelength_variant

and a new variant category

� � � �_variant_variant
� � � �_variant_role
� � � �_variant_timestamp
� � � �_variant_variant_of
� � � �_variant_details

which would allow you with complete generality to manage any number
a refined or redefined quantities, such as wavelengths. �This would
then allow you to us the same variant identifier, for, say cell
dimensions, which could be expected to change in a coupled manner
with the changes in wavelength.

�If you are interested in this more complete approach, I can provide
you with the full item definitions, but the short form is:

� � � �_variant_variant

� � � � � � �The value of _variant_variant must uniquely identify
� � � � � � �each variant for the given diffraction experiment and/or
� � � � � � �entry

� � � �_variant_role

� � � � � � �The value of _variant_role �specifies a role
� � � � � � �for this variant. �Possible roles are null, "preferred",
� � � � � � �"raw data", and "unsuccessful trial".

� � � �_variant_timestamp

� � � � � � �The date and time identifying a variant. �This is not
� � � � � � �necessarily the precise time of the measurement or
� � � � � � �calculation of the individual related data items, but a
timestamp that
� � � � � � �reflects the order in which the variants were defined.

� � � �_variant_variant_of

� � � � � � �The value of _variant.variant_of gives the variant
� � � � � � �from which this variant was derived. �If this value is not
� � � � � � �given, the variant is assumed to be derived from the default
� � � � � � �null variant.

� � � �_variant_details

� � � � � � �A description of special aspects of the variant


� � �An example of how this might be used is:

� � �� � � � loop_
� � �� � � � � � _diffrn_radiation_wavelength_id
� � �� � � � � � _diffrn_radiation_wavelength
� � �� � � � � � _diffrn_radiation_wavelength_determinaton
� � �� � � � � � � �1 � 1.23456 � fundamental
� � �� � � � � � � �2 � 1.25 � � �estimated



would become

� � � � �loop_
� � � � � � �_diffrn_radiation_wavelength_variant
� � � � � � �_diffrn_radiation_wavelength
� � � � � � � � final � 1.23456
� � � � � � � � pelim � 1.25
� � � � �loop_
� � � � � � �_variant_variant
� � � � � � �_variant_role
� � � � � � �_variant_timestamp
� � � � � � �_variant_variant_of
� � � � � � �_variant_details
� � � � � � �final preferred 2007-08-04T01:17:28 prelim refined
� � � � � � �prelim . � � � �2007-08-03T23:20:00 . .

� � � � �loop_
� � � � � � _cell_variant
� � � � � � _cell_length_a
� � � � � � _cell_length_b
� � � � � � _cell_length_c
� � � � � � _cell_angle_alpha
� � � � � � _cell_angle_beta
� � � � � � _cell_angle_gamma
� � � � � � final �22.5 22.5 22.5 90. 90. 90.
� � � � � � prelim 22.3 22.3 22.3 90. 90. 90.


�Regards,
� �Herbert

=====================================================
�Herbert J. Bernstein, Professor of Computer Science
� Dowling College, Kramer Science Center, KSC 121
� � � �Idle Hour Blvd, Oakdale, NY, 11769

� � � � � � � � +1-631-244-3035
� � � � � � � � [email protected]
=====================================================



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