Marine Corps Enlisted Occupation Classification System

The Marine Corps MOS system is composed of occupational fields and MOS's within each field. The occupational system is constructed on the concept that similar skill and knowledge requirements are grouped in functional areas (occupational fields), which provide for the most efficient and effective classification, assignment, promotion, and utilization of personnel.

An MOS code has four digits and a descriptive title. The MOS describes a group of related duties and tasks that extend over one or more grades. The first two digits designate the occupational field and the last two digits identify the promotional channel and the specialty within the occupational field. The fourth digit may be a skill designator, which identifies additional skill or knowledge requirements usually acquired through experience or advanced schooling. A "0" in the fourth digit indicates a basic MOS (see next paragraph), and a "1" indicates trainee status. In some occupational fields, primarily the aviation fields, the skill designator may refer to the particular type of aircraft on which the Marine is qualified.

Each occupational field contains a basic MOS, which represents the learner level (e.g., MOS 6000 is a Basic Aircraft Maintenance Marine). It is assigned as a specific MOS in that field when assigned for training. When in retraining status, a Marine's primary MOS will be changed to the basic MOS.

There are two main categories of MOS's. Category "A" enlisted MOS's (occupational fields 01 through 73) are assigned as primary MOS's. Enlisted personnel are promoted on the basis of holding a category A primary MOS. A category A MOS identifies the primary skill and knowledge of a Marine.

Category "B" MOS's (8000-9599 series) are used to identify billets. They may be assigned only as additional MOS's. These MOS's designate a particular skill or training that is in addition to a Marine's primary MOS.

The relationship between rank and paygrade is shown here:

	Private (PVT)	E-1
	Private First Class (PFC)	E-2
	Lance Corporal (LCP)	E-3
	Corporal (CPL)	E-4
	Sergeant (SGT)	E-5
	Staff Sergeant (SSGT)	E-6
	Gunnery Sergeant (GYSGT)	E-7
	First Sergeant (1STSGT) / Master Sergeant (MSGT)	E-8
	Sergeant Major (SGT/MAJ) / Master Gunnery Sergeant (MGYSGT)	E-9

Performance Evaluation System

Currently, selected aircraft maintenance, avionics, and ground occupational fields have established a performance evaluation system that meets ACE's criteria. Exhibits containing descriptive information on these completed occupation evaluations will appear in the Online Guide, as available. The evaluation programs known as Individual Training Standards System (ITSS) and Maintenance and Training Management and Evaluation Program (MATMEP) provide for the evaluation of a Marine's job performance in the aircraft maintenance and avionics fields. The MATMEP Program is a standardized, documentable, level-progressive, technical skills management and evaluation program for enlisted aviation technical maintenance training.

The ITSS (MATMEP) is organized as a two-way grid. The row headings identify the specific duties and tasks that define an MOS. The column headings identify the skill levels at which each MOS duty and task are performed. When a Marine can perform a particular task at a specified level of skill, the Marine's supervisor evaluates the performance. If the Marine performs satisfactorily, the supervisor dates and signs the ITSS (MATMEP). When all duties and tasks defining a particular skill level can be performed satisfactorily by a Marine, the supervisor dates and signs the ITSS (MATMEP) summary sheet in the location designated "Completed Level ____." When a Marine's ITSS (MATMEP) summary sheet indicates that the Marine has completed Level III, this indicates that all the MOS-requisite tasks have been certified at Level III and that the ACE credit recommendations may be applied.

For aircraft maintenance and avionics MOS's. Marines typically attend one of the formal training schools. This training is then followed by formal and informal on-the-job training at a fleet duty post. The ITSS (MATMEP) Levels I and II reflect the initial training or apprentice levels of an MOS. Upon completion of the initial training school, a Marine is typically certifiable at Level I. After one or two years of post-school on-the-job experience, the Marine may be certified as a Level II performer.

Level III MOS attainment represents an advanced or skilled level of performance of an assigned job and indicates that a Marine can perform the technical aspects of the task or job with little or no supervision. It ordinarily takes three or four years of working in an MOS for a Marine to attain Level III certification.

Level IV indicates that the Marine is a highly skilled performer and is able to supervise lower-skill-level-MOS holders on a regular basis and can perform shop management duties related to the MOS.

A Marine's level of certification is not directly related to the Marine's military rank. Both military rank and skill level are associated with the length of time a Marine has served. The longer the time in service the more likely is a Marine to hold a higher rank and the more likely is a Marine to have acquired a higher level of MOS skill. However, rank and MOS skill proceed on independent tracks in many instances. In certain instances (e.g., when a longer-serving Marine switches from one MOS to another), a corporal may be certified at a higher skill level in a specific MOS than a sergeant in the same MOS.

ACE Credit Recommendations

Credit has been recommended for Levels III and IV in aircraft maintenance and avionics MOS's.

To document proficiency, institutions should verify that Level III or Level IV has been attained by checking the ITSS (MATMEP) summary sheet. This sheet is available to Marines from their duty station supervisors. The form must be signed by a certifying officer.