Navy commissioned officer designations can be somewhat confusing. Unlike the other services which divide their officers into basic branches, the Navy divides their commissioned officers into four basic kinds of officers: Unrestricted Line Officers, Restricted Line Officers, Staff Corps, and Limited Duty Officers. Jobs, assignments, and promotions are based on what kind of an officer one is.
Unrestricted Line Officers are those who are eligible for command of ships, submarines, aircraft squadrons, fleets, and shore bases such as naval bases and naval air stations. These are officers of the line of the Regular Navy and Naval Reserve who are not restricted in the performance of duty. Unrestricted Line Officers are the officers who grow up to become Admirals and command Naval ships and battle groups. Designators (jobs) which fall into the Unrestricted Line Officer category are: Surface Warfare Officers, Pilots, Navy Flight Officers, Aviation Support Officers, Submarine Officers, SEALS, Divers and EOD Officers. These officers are commissioned through the Naval Academy, OCS, and ROTC.
Restricted Line Officers are officers of the line of the Regular Navy and Naval Reserve who are restricted in the performance of duty by having been designated for aviation duty, engineering duty, aerospace engineering duty, or special duty. Examples are: Aviation Maintenance Officers, Specialists in Cryptographic Support, Intelligence, Automatic Data Processing, Public Affairs, and Oceanography. As with Unrestricted Line Officers, these officers are also commissioned through OCS, the Naval Academy, or ROTC.
Those of the Staff Corps are specialists in career fields which are professions unto themselves, such as physicians, nurses, chaplains, lawyers, civil engineers, etc. Staff Corps officers wear their specialty insignia on the sleeve of the dress blue uniforms and on their shoulder boards in place of the star worn by Line officers. These officers are often commissioned through a special "mini-OCS" (5 weeks), or through ROTC.
Limited Duty Officers are former enlisted sailors or warrant officers who are selected for a commission based on extensive training and experience in their enlisted rating (job), or warrant officer occupational field. As the name implies, they are limited to performing their duties as commissioned officers within the field they are selected in. They are commissioned through the LDO Selection Program.
Below are the primary Navy commissioned officer designators: