a matrix and vector would be a useful addition to struct_ncs, perhaps in struct_ens in struct_ncs_ens_oper, and would fill the role of MTRIX from PDB. Though I think this is clearer in ATOM_SITES, and would suggest at least a link, putting it here would at least fill the gap noted in the STRUCT_NCS_ENS_OPER description. -- H. J. Bernstein