text: * Orbifold signature: 
  * Coxeter notation (rhombic): [&infin;,2,&infin;]
  * Coxeter notation (square): [(4,4,2)]
  * Lattice: rhombic
  * Point group: D
  * The group cmm has reflections in two perpendicular directions, and a rotation of order two (180°) whose centre is not on a reflection axis. It also has two rotations whose centres are on a reflection axis.
  *This group is frequently seen in everyday life, since the most common arrangement of bricks in a brick building (running bond) utilises this group (see example below).
  The rotational symmetry of order 2 with centres of rotation at the centres of the sides of the rhombus is a consequence of the other properties.
  The pattern corresponds to each of the following:
  *symmetrically staggered rows of identical doubly symmetric objects
  *a checkerboard pattern of two alternating rectangular tiles, of which each, by itself, is doubly symmetric
  *a checkerboard pattern of alternatingly a 2-fold rotationally symmetric rectangular tile and its mirror image
  ;Examples of group cmm