Wikipedia There is more information available on this subject at Military Occupational Specialty on the English Wikipedia.
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“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 MOS, is a rating system used in the United Nations Space Command Defense Force to describe and explain the job specialty of specific 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.[1]


  1. Bungie Weekly Update: 11/21/08