data_NaCl
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.03
_cell_length_b   4.03
_cell_length_c   5.68
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   89.27
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaCl
_chemical_formula_sum   'Na2 Cl2'
_cell_volume   92.14
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Na  Na2  1  0.87  0.4  0.26  1.0
  Na  Na3  1  0.87  0.6  0.42  1.0
  Cl  Cl0  1  0.87  0.58  0.26  1.0
  Cl  Cl1  1  0.87  0.42  0.42  1.0

data_NaCl
_symmetry_space_group_name_H-M   P2/m
_cell_length_a   4.03
_cell_length_b   4.03
_cell_length_c   5.68
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   10
_chemical_formula_structural   NaCl
_chemical_formula_sum   'Na2 Cl2'
_cell_volume   92.14
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-x, -y, -z'
  3  '-x, y, -z'
  4  'x, -y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Na  Na0  2  0.4  0.0  0.92  1.0
  Cl  Cl1  2  0.42  0.0  0.08  1.0

Na Na Cl Cl