Category: geom_torsion
Data type: char
Must appear in a looped list containing '_geom_torsion_atom_site_label_'
Examples:
. 'no symmetry or translation to site'
4 '4th symmetry operation applied'
7_6455 '7th symm. posn;+a on x;-b on y'
The symmetry code of each atom site as the symmetry operation number 'n' and the higher-dimensional translation 'm1...mp'. These numbers are combined to form the code 'n m1...mp' or n_m1...mp. The character string n_m1...mp is composed as follows: 'n' refers to the symmetry operation that is applied to the superspace coordinates. It must match a number given in _space_group_symop_ssg_id. 'm1...mp' refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (t1,...tp) are related to (m1...mp) by the relations m1=5+t1,...,mp=5+tp. By adding 5 to the translations, the use of negative numbers is avoided. The number 'p' must agree with (_cell_modulation_dimension + 3). If there are no cell translations the translation number may be omitted. If no symmetry operations or translations are applicable then a single period '.' may be used.