Core dictionary (coreCIF) version 2.4.5
Data items in the SYMMETRY_EQUIV category list the symmetry-equivalent positions for the space group.Examples:
Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
[Acta Cryst. (1991), C47, 2276-2277].
loop_ _symmetry_equiv_pos_as_xyz +x,+y,+z 1/2-x,-y,1/2+z 1/2+x,1/2-y,-z -x,1/2+y,1/2-z
Example 2 - based on data set TOZ of Willis, Beckwith & Tozer
[Acta Cryst. (1991), C47, 2276-2277]. Formally, the value of
_symmetry_equiv_pos_site_id can be any unique character string;
it is recommended that it be assigned the sequence number of
the list of equivalent positions for compatibility with
older files in which it did not appear.
loop_ _symmetry_equiv_pos_site_id _symmetry_equiv_pos_as_xyz 1 x,y,z 2 1/2-x,-y,1/2+z 3 1/2+x,1/2-y,-z 4 -x,1/2+y,1/2-z