Category: atom_site_occ_special_func
Data type: char
Must appear in a looped list
Must match a value of '_atom_site_label'
The code that identifies an atom or rigid group in a loop where the parameters of the special function that describe its occupational modulation are being listed. This code must match the _atom_site_label of the associated coordinate list and conform to the rules described in _atom_site_label.