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Re: Transfer from msCIF: refine_ls_class category




Here (at the end of the message) is my attempt at moving the various
categories that relate to reflection classes from the msCIF draft to the
core. I have reworded some definitions to suggest that there is freedom
to assign classes to suit various requirements, but as yet the examples
are all taken from the modulated structures examples.

I am a bit confused about the proper assignment of parent/child
relationships between the new categories. The following diagram indicates
what is done (based largely on Gotzon's original proposals). Two new
pointers have been introduced to existing categories (_refln_class_code and
_diffrn_refln_class_code). The relationships illustrated are "has as parent"
(i.e. _diffrn_reflns_class_code is the parent of the four other data names
indicated, _reflns_class_code is the parent of _refln_class_code). A parent
may have several children; a child can have only one parent.

It seems to me that what this relationship is showing is that the senior
category here is DIFFRN_REFLNS_CLASS, a description of the different groups
of reflections assigned on the raw diffractogram. Individual reflections in
each group are identified through the _diffrn_refln_class_code. REFLNS_CLASS
is a subsidiary category, giving details of the matching groups of
reflections in the structure-factor list. I have thought it useful (or at
least consistent) to allow identification of the individual reflections
through the _refln_class_code.

Now REFLNS_SHELL_CLASS and REFINE_LS_CLASS also appear as subsidiary
categories of the DIFFRN_REFLNS_CLASS one. Does this seem appropriate?
Or should these be linked to the REFLNS_CLASS category instead?

####################################
## EXISTING CATEGORY DIFFRN_REFLN ##
####################################
   _diffrn_refln_class_code ----------------------
#####################################             |
## EXISTING CATEGORY DIFFRN_REFLNS ##             |
#####################################             |
   _diffrn_reflns_number_of_classes               |
#########################                         |
## DIFFRN_REFLNS_CLASS ##                         |
#########################                         |
   _diffrn_reflns_class_[]                        |
   _diffrn_reflns_class_av_R_eq                   |
   _diffrn_reflns_class_av_sgI/I                  |
 * _diffrn_reflns_class_code <=======================----
   _diffrn_reflns_class_number_of_reflns             | | |
   _diffrn_reflns_class_d_res_high                   | | |
   _diffrn_reflns_class_d_res_low                    | | |
   _diffrn_reflns_class_description                  | | |
#####################                                | | |
## REFINE_LS_CLASS ##                                | | |
#####################                                | | |
   _refine_ls_class_[]                               | | |
 * _refine_ls_class_code ---------------->-----------  | |
   _refine_ls_class_d_res_high                         | |
   _refine_ls_class_d_res_low                          | |
   _refine_ls_class_R_factor_all                       | |
   _refine_ls_class_R_factor_gt                        | |
   _refine_ls_class_R_Fsqd_factor                      | |
   _refine_ls_class_R_I_factor                         | |
   _refine_ls_class_wR_factor_all                      | |
#############################                          | |
## EXISTING CATEGORY REFLN ##                          | |
#############################                          | |
   _refln_class_code --->--                            | |
##################         |                           | |
## REFLNS_CLASS ##         |                           | |
##################         |                           | |
   _reflns_class_[]        |                           | |
                      <----                            | |
 * _reflns_class_code ------------------->-------------- |
   _reflns_class_number_of_reflns_total                  |
   _reflns_class_number_of_reflns_gt                     |
########################                                 |
## REFLNS_SHELL_CLASS ##                                 |
########################                                 |
   _reflns_shell_class_[]                                |
 * _reflns_shell_class_code ------------->---------------
   _reflns_shell_class_d_res_high
   _reflns_shell_class_d_res_low
   _reflns_shell_class_meanI_over_sigI_all
   _reflns_shell_class_meanI_over_sigI_gt
   _reflns_shell_class_number_measured_all
   _reflns_shell_class_number_measured_gt
   _reflns_shell_class_number_possible
   _reflns_shell_class_number_unique_all
   _reflns_shell_class_number_unique_gt
   _reflns_shell_class_percent_possible_all
   _reflns_shell_class_percent_possible_gt
   _reflns_shell_class_Rmerge_F_all
   _reflns_shell_class_Rmerge_F_gt
   _reflns_shell_class_Rmerge_I_all
   _reflns_shell_class_Rmerge_I_gt

I note also that the DIFFRN_REFLNS category has the new dataname
_diffrn_reflns_number_of_classes. There is, however, no matching
_reflns_number_of_classes in the REFLNS category. Should there be?

Regards
Brian


==============================================================================
####################################
## EXISTING CATEGORY DIFFRN_REFLN ##
####################################

data_diffrn_refln_class_code
    _name                      '_diffrn_refln_class_code'
    _category                    diffrn_refln
    _type                        char
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _list_link_parent          '_diffrn_reflns_class_code'
    _definition
;              The code identifying the class to which this reflection has been
               assigned. This code must match a value of
               _diffrn_reflns_class_code.  Reflections may be grouped into
               classes for a variety of purposes.  For example, for modulated
               structures each reflection class may be
               defined by the number m=sum|mi|, where the mi are the integer
               coefficients that, in addition to h,k,l, index the corresponding
               diffraction vector in the basis defined for the reciprocal cell.

;

####################################
## EXISTING CATEGORY DIFFRN_REFLN ##
####################################

data_diffrn_reflns_number_of_classes
    _name                      '_diffrn_reflns_number_of_classes'
    _category                    diffrn_reflns
    _type                        numb
    _definition
;              Number of different intensity classes measured. Reflections
               may be grouped into classes for a variety of purposes. For
               example, for modulated structures each reflection class may
               be defined by the number m=sum|mi|, where the mi are the
               integer coefficients that, in addition to h,k,l, index the
               corresponding diffraction vector in the basis defined for the
               reciprocal cell.
;

#########################
## DIFFRN_REFLNS_CLASS ##  
#########################

data_diffrn_reflns_class_[]
    _name                      '_diffrn_reflns_class_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
        _diffrn_reflns_class_number_of_reflns
        _diffrn_reflns_class_d_res_high
        _diffrn_reflns_class_d_res_low
        _diffrn_reflns_class_av_R_eq
        _diffrn_reflns_class_code
        _diffrn_reflns_class_description
               1580 0.551 6.136 0.015 'Main' 'm=0; main reflections'
               1045 0.551 6.136 0.010 'Sat1' 'm=1; first-order satellites'
;
;
    Example 1 - example corresponding to the one-dimensional incommensurately 
                modulated structure of K~2~SeO~4~. Each reflection class is
                defined by the number m=sum|mi|, where the mi are the integer
                coefficients that, in addition to h,k,l, index the
                corresponding diffraction vector in the basis defined for the
                reciprocal cell.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      _definition
;              Data items in the DIFFRN_REFLNS_CLASS category record details 
               about the classes of reflections measured in the diffraction
               experiment.
;

data_diffrn_reflns_class_av_R_eq
    _name                      '_diffrn_reflns_class_av_R_eq'
    _category                    diffrn_reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_reflns_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the residual 
               [sum|avdel(I)|/sum|av(I)|] for symmetry-equivalent reflections 
               used to calculate the average intensity av(I). The avdel(I) term
               is the average difference between av(I) and the individual 
               intensities.
;

data_diffrn_reflns_class_av_sgI/I
    _name                      '_diffrn_reflns_class_av_sgI/I'
    _category                    diffrn_reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_reflns_class_code'
    _enumeration_range           0.0:
    _definition
;              Measure [sum|sigma(I)|/sum|net(I)|] for all measured intensities
               in a reflection class.
;

data_diffrn_reflns_class_code
    _name                      '_diffrn_reflns_class_code'
    _category                    diffrn_reflns_class
    _type                        char
    _list                        yes
    _list_mandatory              yes
    loop_ _list_link_child     '_diffrn_refln_class_code'
                               '_refine_ls_class_code'
                               '_reflns_class_code'
                               '_reflns_shell_class_code'
    loop_ _example               '1'
                                 'm1'
                                 's2'
    _definition
;              The code identifying a certain reflection class.
;

data_diffrn_reflns_class_number_of_reflns
    _name                      '_diffrn_reflns_class_number_of_reflns'
    _category                    diffrn_reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_reflns_class_code'
    _enumeration_range           0:
    _definition
;              The total number of measured intensities for each reflection 
               class, excluding the systematic extinctions arising from 
               centering translations.
;

data_diffrn_reflns_class_d_res_
    loop_ _name                '_diffrn_reflns_class_d_res_high'
                               '_diffrn_reflns_class_d_res_low'
    _category                    diffrn_reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_reflns_class_code'
    _enumeration_range           0.0:
    _units                       A
    _units_detail                'Angstroms'
    _definition
;              The highest and lowest resolution in angstroms for the 
               interplanar spacing in the reflections of each measured 
               reflection class. They are the smallest and the highest d values
               for each reflection class.
;

data_diffrn_reflns_class_description
    _name                      '_diffrn_reflns_class_description'
    _category                    diffrn_reflns_class
    _type                        char
    _list                        yes
    _list_reference            '_diffrn_reflns_class_code'
    loop_ _example               'm=1 first order satellites'
                                 'H0L0 common projection reflections'
    _definition
;              Description of each reflection class. Number of definitions must
               match the number given in _diffrn_reflns_number_of_classes.
;


#####################
## REFINE_LS_CLASS ##   
#####################

data_refine_ls_class_[]
    _name                      '_refine_ls_class_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
        _refine_ls_class_R_factor_gt
        _refine_ls_class_code
                0.057    'Main'
                0.074    'Com'
                0.064    'NbRefls'
                0.046    'LaRefls'
                0.112    'Sat1'
                0.177    'Sat2'
;
;
    Example 1 - example for a modulated structure extracted from van Smaalen
                [(1991). J. Phys.:Condens. Matter, 3, 1247-1263.]
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      _definition
;              Data items in the REFINE_LS_CLASS category record details 
               (for each reflection class separately) about the reflections used
               for the structure refinement.
;

data_refine_ls_class_code
    _name                      '_refine_ls_class_code'
    _category                    refine_ls_class
    _type                        char
    _list                        yes
    _list_link_parent          '_diffrn_reflns_class_code'
    loop_ _example               '1'
                                 'm1'
                                 's2'
    _definition
;              The code identifying a certain reflection class. This code must 
               match a _diffrn_reflns_class_code.
;

data_refine_ls_class_d_res_high
    _name                      '_refine_ls_class_d_res_high'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference            '_refine_ls_class_code'
    _enumeration_range           0.0:
    _units                       A
    _units_detail                'Angstroms'
    _definition
;              For each reflection class, the highest resolution in angstroms
               for the spacing in the reflections used in refinement. This is
               the lowest d value in a reflection class.
;

data_refine_ls_class_d_res_low
    _name                      '_refine_ls_class_d_res_low'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference            '_refine_ls_class_code'
    _enumeration_range           0.0:
    _units                       A
    _units_detail                'Angstroms'
    _definition
;              For each reflection class, the lowest resolution in angstroms 
               for the spacing in the reflections used in refinement. This is
               the highest d value in a reflection class.
;

data_refine_ls_class_R_factor_
    loop_ _name                '_refine_ls_class_R_factor_all'
                               '_refine_ls_class_R_factor_gt'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference            '_refine_ls_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the residual factors for all 
               reflections, and for significantly intense reflections (see 
               _reflns_threshold_expression) and included in the refinement.
               The reflections also satisfy the resolution limits established by
               _refine_ls_class_d_res_high and _refine_ls_class_d_res_low.
               This is the conventional R factor. 
                        R=sum|F(obs)-F(calc)|/sum|F(obs)|
               F(obs)=the observed structure-factor amplitudes, F(calc)=the 
               calculated structure-factor amplitudes, and the sum is taken over
               the specified reflections. See also 
               _refine_ls_class_wR_factor_all definitions.
;

data_refine_ls_class_R_Fsqd_factor
    _name                      '_refine_ls_class_R_Fsqd_factor'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference            '_refine_ls_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the residual factor R(F^2^) calculated
               on the squares of the observed and calculated structure factors,
               for the reflections judged significantly intense (i.e. satisfying
               the threshold specified by _reflns_threshold_expression) and 
               included in the refinement. The reflections also satisfy the 
               resolution limits established by _refine_ls_class_d_res_high and
               _refine_ls_class_d_res_low.
                        R(F^2^)=sum|F(obs)^2^-F(calc)^2^|/sum|F(obs)^2^|
               F(obs)^2^=squares of the observed structure-factor amplitudes, 
               F(calc)^2^=squares of the calculated structure-factor amplitudes,
               and the sum is taken over the specified reflections.
;

data_refine_ls_class_R_I_factor
    _name                      '_refine_ls_class_R_I_factor'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference            '_refine_ls_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the residual factor R(I) for the
               reflections judged significantly intense (i.e. satisfying the
               threshold specified by _reflns_threshold_expression) and
               included in the refinement.

               This is most often calculated in Rietveld refinements
               of powder data, where it is referred to as R~B~ or R~Bragg~
                        R(I)=sum|I(obs)-I(calc)|/sum|I(obs)|
               I(obs)=the net observed intensities, I(calc)=the net calculated
               intensities, and the sum is taken over the specified reflections
;

data_refine_ls_class_wR_factor_all
    _name                      '_refine_ls_class_wR_factor_all'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference            '_refine_ls_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the weighted residual factors for all 
               reflections and included in the refinement. The reflections also
               satisfy the resolution limits established by
               _refine_ls_class_d_res_high and _refine_ls_class_d_res_low.
                        wR=sum|w|Y(obs)-Y(calc)|^2^|^1/2^/sum|wY(obs)^2^|
               Y(obs)=the observed amplitude specified by 
               _refine_ls_structure_factor_coef, Y(calc)=the calculated 
               amplitude specified by _refine_ls_structure_factor_coef, w=the
               least-squares weight, and the sum is taken over the specified 
               reflections. See also _refine_ls_class_R_factor_ definitions.
;

#############################
## EXISTING CATEGORY REFLN ##
#############################

data_refln_class_code
    _name                      '_refln_class_code'
    _category                    refln
    _type                        char
    _list                        yes
    _list_reference            '_refln_index_'
    _list_link_parent          '_reflns_class_code'
    _definition
;              The code identifying the class to which this reflection has been
               assigned. This code must match a value of _reflns_class_code.
               Reflections may be grouped into classes for a variety of purposes.
               For example, for modulated structures each reflection class may be
               defined by the number m=sum|mi|, where the mi are the integer
               coefficients that, in addition to h,k,l, index the corresponding
               diffraction vector in the basis defined for the reciprocal cell.
;

##################
## REFLNS_CLASS ##    
##################

data_reflns_class_[]
    _name                        '_reflns_class_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
        _reflns_class_number_of_reflns_gt
        _reflns_class_code
               584     'Main'
               226     'Sat1'
               50      'Sat2'
;
;
    Example 1 - example corresponding to the one-dimensional incommensurately 
                modulated structure of K~2~SeO~4~.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      _definition
;              Data items in the REFLNS_CLASS category record details, for
               each reflection class, about the reflections used to determine
               the structural parameters.
;

data_reflns_class_code
    _name                      '_reflns_class_code'
    _category                    reflns_class
    _type                        char
    _list                        yes
    _list_link_child           '_refln_class_code'
    _list_link_parent          '_diffrn_reflns_class_code'
    loop_ _example               '1'
                                 'm1'
                                 's2'
    _definition
;              The code identifying a certain reflection class. This code must 
               match a _diffrn_reflns_class_code.
;

data_reflns_class_number_of_reflns_
    loop_ _name                '_reflns_class_number_of_reflns_total'
                               '_reflns_class_number_of_reflns_gt'
    _category                    reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the total number of reflections, and
               the number of significantly intense reflections (see 
               _reflns_threshold_expression) in the _refln_ list (not the 
               _diffrn_refln_ list). They may include Friedel equivalent
               reflections according to the nature of the structure and the 
               procedures used. The item _reflns_special_details describes the
               reflection data.
;

########################
## REFLNS_SHELL_CLASS ## 
########################

data_reflns_shell_class_[]
    _name                      '_reflns_shell_class_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
       No example
;
;
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      _definition
;              Data items in the REFLNS_SHELL_CLASS category record details, for
               each reflection class, about the reflections used to determine
               the structural parameters, as broken down by shells of 
               resolution.
;

data_reflns_shell_class_code
    _name                      '_reflns_shell_class_code'
    _category                    reflns_shell_class
    _type                        char
    _list                        yes
    _list_link_parent          '_diffrn_reflns_class_code'
    loop_ _example               '1'
                                 'm1'
                                 's2'
    _definition
;              The code identifying a certain reflection class. This code must 
               match a _diffrn_reflns_class_code.
;

data_reflns_shell_class_d_res_high
    _name                      '_reflns_shell_class_d_res_high'
    _category                    reflns_shell_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_shell_class_code'
    _enumeration_range           0.0:
    _units                       A
    _units_detail                'Angstroms'
    _definition
;              For each reflection class the highest resolution in angstroms for
               the interplanar spacing in the reflections in this shell. This is
               the smallest d value.
;

data_reflns_shell_class_d_res_low
    _name                      '_reflns_shell_class_d_res_low'
    _category                    reflns_shell_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_shell_class_code'
    _enumeration_range           0.0:
    _units                       A
    _units_detail                'Angstroms'
    _definition
;              For each reflection class the lowest resolution in angstroms for 
               the interplanar spacing in the reflections in this shell. This is
               the largest d value.
;

data_reflns_shell_class_meanI_over_sigI_all
    _name                      '_reflns_shell_class_meanI_over_sigI_all'
    _category                    reflns_shell_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_shell_class_code'
    _definition
;              For each reflection class the ratio of the mean of the 
               intensities of all reflections in this shell to the mean of the
               standard uncertainties of the intensities of all reflections in
               the resolution shell.
;
 
data_reflns_shell_class_meanI_over_sigI_gt
    _name                      '_reflns_shell_class_meanI_over_sigI_gt'
    _category                    reflns_shell_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_shell_class_code'
    _definition
;              For each reflection class the ratio of the mean of the 
               intensities of the reflections judged significantly intense (see 
               _reflns_threshold_expression) in this shell to the mean of the 
               standard uncertainties of the significantly intense reflections 
               in the resolution shell.
;
 
data_reflns_shell_class_number_measured_all
    _name                      '_reflns_shell_class_number_measured_all'
    _category                    reflns_shell_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_shell_class_code'
    _enumeration_range           0:
    _definition
;              For each reflection class the total number of reflections 
               measured for this resolution shell.
;
 
data_reflns_shell_class_number_measured_gt
    _name                      '_reflns_shell_class_number_measured_gt'
    _category                    reflns_shell_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_shell_class_code'
    _enumeration_range           0:
    _definition
;              For each reflection class the number of reflections judged 
               significantly intense (see _reflns_threshold_expression) measured
               for this resolution shell.
;

data_reflns_shell_class_number_possible
    _name                      '_reflns_shell_class_number_possible'
    _category                    reflns_shell_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_shell_class_code'
    _enumeration_range           0:
    _definition
;              For each reflection class the number of unique reflections it is
               possible to measure in this reflection shell.
;

data_reflns_shell_class_number_unique_all
    _name                      '_reflns_shell_class_number_unique_all'
    _category                    reflns_shell_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_shell_class_code'
    _enumeration_range           0:
    _definition
;              For each reflection class the total number of measured 
               reflections remaining after merging symmetry equivalent 
               reflections for this resolution shell.
;

data_reflns_shell_class_number_unique_gt
    _name                      '_reflns_shell_class_number_unique_gt'
    _category                    reflns_shell_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_shell_class_code'
    _enumeration_range           0:
    _definition
;              For each reflection class the total number of reflections 
               judged significantly intense (see _reflns_threshold_expression)
               remaining after merging symmetry equivalent reflections for this 
               resolution shell. 
;

data_reflns_shell_class_percent_possible_all
    _name                      '_reflns_shell_class_percent_possible_all'
    _category                    reflns_shell_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_shell_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class the percentage of geometrically 
               possible reflections represented by all reflections measured for
               this resolution shell.
;

data_reflns_shell_class_percent_possible_gt
    _name                      '_reflns_shell_class_percent_possible_gt'
    _category                    reflns_shell_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_shell_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class the percentage of geometrically 
               possible reflections represented by significantly intense 
               reflections (see _reflns_threshold_expression) measured for this
               resolution shell.
;

data_reflns_shell_class_Rmerge_F_all
    _name                      '_reflns_shell_class_Rmerge_F_all'
    _category                    reflns_shell_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_shell_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class the value of Rmerge(F) for all 
               reflections in a given shell.
 
                           sum~i~ ( sum~j~ | F~j~ - <F> | )
               Rmerge(F) = --------------------------------
                               sum~i~ ( sum~j~ <F> )
 
               F~j~= the amplitude of the jth observation of reflection i
               <F> = the mean of the amplitudes of all observations of
                     reflection i
 
               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;

data_reflns_shell_class_Rmerge_F_gt
    _name                      '_reflns_shell_class_Rmerge_F_gt'
    _category                    reflns_shell_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_shell_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class the value of Rmerge(F) for reflections
               judged significantly intense (see _reflns_threshold_expression)
               in a given shell.
 
                           sum~i~ ( sum~j~ | F~j~ - <F> | )
               Rmerge(F) = --------------------------------
                               sum~i~ ( sum~j~ <F> )
 
               F~j~= the amplitude of the jth observation of reflection i
               <F> = the mean of the amplitudes of all observations of
                     reflection i
 
               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;

data_reflns_shell_class_Rmerge_I_all
    _name                      '_reflns_shell_class_Rmerge_I_all'
    _category                    reflns_shell_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_shell_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class the value of Rmerge(I) for all 
               reflections in a given shell.
 
                           sum~i~ ( sum~j~ | I~j~ - <I> | )
               Rmerge(I) = --------------------------------
                               sum~i~ ( sum~j~ <I> )
 
               I~j~= the intensity of the jth observation of reflection i
               <I> = the mean of the intensities of all observations of
                     reflection i
 
               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;

data_reflns_shell_class_Rmerge_I_gt
    _name                      '_reflns_shell_class_Rmerge_I_gt'
    _category                    reflns_shell_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_shell_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class the value of Rmerge(I) for 
               significantly intense reflections (see 
               _reflns_threshold_expression) in a given shell.
 
                           sum~i~ ( sum~j~ | I~j~ - <I> | )
               Rmerge(I) = --------------------------------
                               sum~i~ ( sum~j~ <I> )
 
               I~j~= the intensity of the jth observation of reflection i
               <I> = the mean of the intensities of all observations of
                      reflection i
 
               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;
==============================================================================


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