Data items in the PDBX_REFERENCE_ENTITY_NONPOLY category record the list of entities within each reference molecule.
loop_ _pdbx_reference_entity_nonpoly.prd_id _pdbx_reference_entity_nonpoly.ref_entity_id _pdbx_reference_entity_nonpoly.name _pdbx_reference_entity_nonpoly.chem_comp_id PRD_000004 2 "2-CARBOXYQUINOXALINE" QUI