John, There may be a typo here in mmCIF 0.9.0 save__phasing_set.id _item_description.description ; The value of _phasing_set.id must uniquely identify a record in the PHASING_SET list. Note that this item need not be a number; it can be any unique identifier. ; loop_ _item.name _item.category_id _item.mandatory_code '_phasing_set.id' phasing_set yes '_phasing_set_refln.set_id' phasing_set_refln yes '_phasing_MAD_set.set_id' phasing_MAD_set yes '_phasing_MIR_der.der_set_id' phasing_MIR_der yes '_phasing_MIR_der.native_set_id' phasing_MIR_der yes '_phasing_MIR_der_refln.set_id' phasing_MIR_der_refln yes loop_ _item_linked.child_name _item_linked.parent_name '_phasing_set_refln.set_id' '_phasing_set.id' '_phasing_MAD_set.set_id' '_phasing_set.id' '_phasing_MIR_der.der_set_id' '_phasing_set.id' '_phasing_MIR_der.native_set_id' '_phasing_set.id' '_phasing_MIR_der_refln.set_id' '_phasing_set.id' _item_type.code line loop_ _item_examples.case 'KAu(CN)2' 'K2HgI4' save_ -- ==================================================================== Jiansheng Jiang Ph.D. | Protein Data Bank | Phone: (516) 344-6388 Biology Department, Bldg 463 | Fax: (516) 344-5751 Brookhaven National Laboratory | mailto://jiang@bnl.gov Upton NY 11973-5000, USA | http://www.pdb.bnl.gov/~jiang ====================================================================