p1        oblique
p2        oblique
pm        rectangular
pg        rectangular
cm        rectangular
p2mm      rectangular
p2mg      rectangular
p2gg      rectangular
c2mm      rectangular
p4        square
p4mm      square
p4gm      square
p3        hexagonal
p3m1      hexagonal
p31m      hexagonal
p6        hexagonal
p6mm      hexagonal
