              Weighted residual factor wR for reflections that satisfy the\
               resolution limits established by _refine.ls_d_res_high and\
               _refine.ls_d_res_low and the observation limit established by\
               _reflns.observed_criterion, and that were used as the test\
               (i.e., excluded from refinement) reflections when refinement\
               included calculation of a "free" R factor. Details of how\
               reflections were assigned to the working and test sets are\
               given in _reflns.R_free_details.\
\
                    ( sum|w |Y~obs~ - Y~calc~|^2^| )^1/2^\
               wR = ( ---------------------------- )\
                    (        sum|w Y~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\
\
               sum is taken over the specified reflections