Macromolecular dictionary (mmCIF) version 2.0.09
The number of reflections that satisfy the resolution limits established by _refine_hist.d_res_high and _refine_hist.d_res_low and the observation limit established by _reflns.observed_criterion, and that were used as the test reflections (i.e. were excluded from the refinement) when the refinement included the 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.
Mandatory item: no
The permitted range is [0, infinity)