Variants
James Hester
jamesrhester at gmail.com
Wed Nov 25 23:59:19 GMT 2009
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
yaya at dowling.edu
=====================================================
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