For each reflection class, the total number of reflections
in the REFLN list (not the DIFFRN_REFLN list). This may
include Friedel-equivalent reflections (i.e. those which are
symmetry-equivalent under the Laue symmetry but inequivalent
under the crystal class) according to the nature of the
structure and the procedures used. Any special characteristics
of the reflections included in the REFLN list should be
described using the item _reflns.details.