The U.S. Navy has several ratings or job specialties for its enlisted members; see List of United States Navy ratings for more details.
An enlisted member is known by the enlisted rating, for example, a Machinist's Mate (or MM), and/or by the enlisted rate, for example Petty Officer First Class (or PO1). Often Navy enlisted members are addressed by a combination of rating and rate. In this example, this machinist's mate petty officer first class may be addressed as Machnist's Mate 1st Class (or MM1).
However, the NEC designator is a four-digit code that identifies skills and abilities beyond the standard (or outward) rating designator. According to the Military Personnel Manual (MILSPERMAN) 1221-010, the NEC designator facilitates personnel planning, procurement, and selection for training; development of training requirements; promotion, distribution, assignment and the orderly call to active duty of inactive duty personnel in times of national emergency or mobilizaton.
For example, a person holding the MM-3385 is a nuclear-trained machinist's mate for surface ships, and a person with an MM-3355 is a nuclear-trained machinist's mate for submarines.
In the U.S. Navy's officer ranks, the naval officer designator serves as similar purpose.
Navy Announces Updated Special Duty Assignment Pay Rates Story Number: Nns130326-07 Release Date: 3/ 26/ 2013 3:28:00 Pm
Mar 26, 2013; MILLINGTON, Tenn. (NNS) -- The following information was released by the Navy: By Mass Communication Specialist 2nd Class Andrea...