MIL-STD-1559A (NOTICE 2), MILITARY STANDARD: NUMBERS, SERIAL, AIRCRAFT GAS TURBINE ENGINE AND ENGINE MODULE ASSIGNMENT OF (14 JUN 1991) [S/S BY MIL-HDBK-1559A]., The following changes form A part of MIL-STD_1559A, dated 1 January 1984, and is approved for use by all departments and agencies of the Department of Defense