Military Occupational Specialty

"Potential volunteers are recruited for service with the ODSTs because of their performance in their chosen MOS"

- Description of ODST entry requirements.

A Military Occupational Specialty, abbreviated to MOS, is a rating system used in the United Nations Space Command Defense Force to describe the job specialty of personnel. Different services, such as the Army, Air Force, Navy and Marine Corps use different ratings, but all have a system to classify personnel based on their occupation.