Data items in the NDB_ENTITY_POLY_DOMAIN category specify domains of monomers within a polymer.
_ndb_entity_poly_domain.begin_mon_id _ndb_entity_poly_domain.begin_seq_num _ndb_entity_poly_domain.end_mon_id _ndb_entity_poly_domain.end_seq_num _ndb_entity_poly_domain.entity_id _ndb_entity_poly_domain.id