P 21 21 2,Nr.18*Czech*
LATT -1
SYMM  -X,-Y,Z
SYMM  0.5+X,0.5-Y,-Z
SYMM  0.5-X,0.5+Y,-Z
    0 .5 / 0 .5 / 0 1
    P 21 21 2,Nr.18*Czech*