space group	number
Pmm2 = P2mm=Pm2m	25
Pmc21 = P21ma = Pb21m = Pm21b = Pcm21 = P21am	26
Pcc2 = P2aa = Pb2b	27
Pma2 = P2mb = Pc2m = Pm2a = Pbm2 = P2cm	28
Pca21 = P21ab = Pc21b = Pb21a = Pbc21 = P21ca	29
Pnc2 = P2na = Pb2n = Pn2b = Pcn2 = P2an	30
Pmn21 = P21mn = Pn21m = Pm21n = Pnm21 = P21nm	31
Pba2 = P2cb = Pc2a	32
Pna21 = P21nb = Pc21n = Pn21a = Pbn21 = P21cn	33
Pnn2 = P2nn=Pn2n	34
Cmm2 = A2mm=Bm2m	35
Cmc21 = A21ma = Bb21m = Bm21b = Ccm21 = A21am	36
Ccc2 = A2aa = Bb2b	37
Amm2 = B2mm=Cm2m= Am2m = Bmm2 = C2mm	38
Abm2 = B2cm=Cm2a= Ac2m = Bma2 = C2mb	39
Ama2 = B2mb=Cc2m= Am2a = Bmb2 = C2cm	40
Aba2 = B2cb=Cc2a=  Ac2a = Bba2 = C2cb	41
Fmm2 = F2mm=Fm2m	42
Fdd2 = Fdd2=Fd2d	43
Imm2 = I2mm=Im2m	44
Iba2 = I2cb = Ic2a	45
Ima2 = I2mb = Ic2m =  Im2a = Ibm2 = I2cm	46