Wallpaper group 8 of 17, pgg: a rectangular lattice, point group 2mm, 4 operations per cell, orbifold 22×. Written p2gg in full.
Molecular point groups with their operations and character tables, the 230 space groups with a cell builder, and the 17 wallpaper and 7 frieze groups drawn live. The tool needs JavaScript, and WebGL2 for the 3D views; these are the pages it offers: