(Return link to main list of space groups in standard settings.)
| (a). C 4 / a m m with origin at -42m. |
| (b). C 4 / a m m with origin at 2/m and 4mm at 1/4,0,z. |
| (c). C 4 / a m m with origin at 2/m and -42m at 1/4,0,0. |
| (d). C 4 / a m m with origin at 4mm and 2/m at 1/4,0,0. |