9.20: Twinning by reticular polyholohedry
Twinning by reticular polyholohedry is a special case of twinning by reticular merohedry that occurs when the twin lattice has the same point group as the lattice of the individual but at least one of its symmetry elements is differently oriented in space.
When the point group of the twin lattice is only close to that of the individual lattice one speaks of twinning by reticular pseudopolyholohedry , which corresponds to non-zero twin obliquity.