Page "Frieze group" Paragraph 4

A symmetry group of a frieze group necessarily contains translations and may contain glide reflections.

Other possible group elements are reflections along the long axis of the strip, reflections along the narrow axis of the strip and 180 ° rotations.

For two of the seven frieze groups ( numbers 1 and 2 below ) the symmetry groups are singly generated, for four ( numbers 3 – 6 ) they have a pair of generators, and for number 7 the symmetry groups require three generators.