The Army and Marine Corps use established mechanisms that allow them to categorize and track personnel with specific skill sets. Specifically, each service uses Military Occupational Specialties (MOS) and additional skill identifiers to categorize the specific jobs and skill sets of officers and enlisted servicemembers. Department of the Army Pamphlet 600-3, Department of the Army Pamphlet 600-25, Department of the Army Pamphlet 611-21, and the Marine Corps' Military Occupational Specialties Manual outline the MOS and skill identifiers for officers and enlisted personnel.