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 Marine Corps 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 are used along with the Navy Enlisted Classification (NEC) system. A system of ratings is also used in the United States Coast Guard.

Since an individual can obtain multiple job specialties, a duty military occupational specialty (DMOS) is used to identify what their primary job function is at any given time. An individual must complete and pass all required training for their military occupational specialty qualification (MOSQ).

Originally, the four-digit MOS code mostly listed the recruit's civilian profession. This was to aid in classifying what military job they could be assigned. With so many recruits being processed, identifying any semi-skilled or skilled civilian tradesmen made it easier to match them with the right military job. There was an additional list of military trades and trainings added so a trained soldier could be assigned to the right unit. There were no grouping of similar trades together, making it hard for someone to know the meaning of an MOS code without a manual.

The MOS system now had five digits, with a period after the third digit. The first four-digit code number indicated the soldier's job; the first two digits were the field code, the third digit was the sub-specialty and the fourth code number (separated by a period) was the job title. A fifth code digit was for the soldier's special qualification identifier (SQI) digit, which indicated what specialized training the soldier had. If the soldier did not have an SQI, the digit was listed as "0" or was omitted. The codes for the civilian trades were removed as unnecessary.

In 1964 the system was revamped. There were completely different codes for enlisted / non-commissioned officers, warrant officers, and commissioned officers.

Enlisted and NCO personnel had a five-symbol code. The first four code symbols were made up of a two-digit code for the career field, a letter code for the field specialty, and a number code (1 to 5) indicating level of instruction in their field specialty. The fifth code symbol was an SQI code letter indicating training in a special skill (the letter "O" indicating that the soldier had no SQI). An exception to the 5-symbol rule was made for an SQI which indicated language fluency. In this case, 7 symbols were used, with "L" as the language qualification indicator, followed by two characters indicating the specific language.

Warrant officers also had a five-symbol code but it was different. The first three numbers were the career field, then a letter code for the field specialty, and ended in the SQI code letter.

Officers had a four-digit code number for their career field and specialty. Officers with a special qualification also had an SQI code number prefix to their MOS rather than a code letter suffix. Officers without a special qualification had no prefix number.