H2O               ! my name for the system
?                 ! scaling parameter
 ? 0 0            ! lattice vector a
 0 ? 0            ! lattice vector b
 0 0 ?            ! lattice vector c
? ?               ! number of atoms
cart              ! positions in cartesian coordinates
      0.00     0.00     0.00   F F F ! O
      ?        ?        0.00   T T F ! H
      ?        ?        0.00   ? ? ? ! H
