text: * Orbifold signature: 
  * Coxeter notation: [&infin;,2,&infin;] or [&infin;,2,&infin;]
  * Lattice: rhombic
  * Point group: D
  * The group cm contains no rotations. It has reflection axes, all parallel. There is at least one glide reflection whose axis is not a reflection axis; it is halfway between two adjacent parallel reflection axes.
  *This group applies for symmetrically staggered rows (i.e. there is a shift per row of half the translation distance inside the rows) of identical objects, which have a symmetry axis perpendicular to the rows.
  ;Examples of group cm