Crystallographic point group

In crystallography, a crystallographic point group is a three-dimensional point group whose symmetry operations are compatible with the translational symmetry of three-dimensional crystallographic lattices. According to the crystallographic restriction it may only contain one-, two-, three-, four- and sixfold rotations or rotoinversions (Note that inversion centers and mirror planes are included as equivalent operations to one-fold and two-fold rotoinversions).

Source: Wikipedia — Crystallographic point group (CC BY-SA 4.0)