MIL-STD-1661, MILITARY STANDARD: MARK AND MOD NOMENCLATURE SYSTEM (01 AUG 1978)., This standard sets forth procedures for establishing and changing item names and designations of systems, equipments, and material items under the cognizance of the Naval Sea Systems Command and, when officially requested, systems, equipments, and material items under the cognizance of the Naval Air Systems Command. This standard defines the MARK and MOD system of nomenclature and gives instructions for processing requests for assignment of nomenclature.