Completeness (as a percentage) of symmetry-unique
anomalous difference data within the intersection of
(1) a sphere (defined by the diffraction limits,
_reflns.d_resolution_high and _reflns.d_resolution_low)
and (2) the ellipsoid (described by
__reflns.pdbx_aniso_diffraction_limit_* items),
relative to all possible symmetry-unique anomalous
difference data within that intersection.