XmlmmCIF equivalent: atom_sites_alt Data items in the ATOM_SITES_ALT category record details about the structural ensembles that should be generated from atom sites or groups of atom sites that are modeled in alternative conformations in this data block. XmlmmCIF equivalent: atom_sites_alt/details A description of special aspects of the modeling of atoms in alternative conformations. XmlmmCIF equivalent: atom_sites_alt/id The value of _atom_sites_alt.id must uniquely identify a record in the ATOM_SITES_ALT list. Note that this item need not be a number; it can be any unique identifier.