The number of 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
reflections (i.e. were excluded from the refinement) when the
refinement included the calculation of a 'free' R factor,
expressed as a percentage of the number of geometrically
observable reflections that satisfy the resolution limits.