what is the meaning of m o s
United States military occupation code A United States military occupation code, or a military occupational specialty code (MOS code), is a nine-character code used in the United States Army and United States Marines to identify a specific job. In the United States Air Force, a system of Air Force Specialty Codes (AFSC) is used. In the United States Navy, a system of naval ratings and designators was used along with the Navy Enlisted Classification (NEC) system: however, on September 29, 2016, the United States Navy discontinued enlisted ratings after two hundred and forty-one years of use. Naval service members thereafter were to be referred to solely by their rank and would hold a Navy Operations Specialty (NOS) instead of a rate.