This is a list of Naval Officer Designators in the United States Navy.
In the United States Navy officers are assigned to one of four communities, based on their education, training and assignments: Line Officers (divided into Unrestricted Line or URL, Restricted Line or RL, and Restricted Line Special Duty or RL SD), Staff Corps Officers, Limited Duty Officers (LDO), or Warrant Officers (WO/CWO). Each community is further subdivided by primary occupation. Each occupation is identified by a four digit numerical code, called a designator.
The first digit identifies the officer's community.
The second and third digits denotes the officer's area of specialization within the Line, Staff Corps, LDO or Warrant Officer communities.
The final (fourth) digit denotes the officer's current type of commission.
Between Fiscal Year 1992 until Fiscal Year 2005, all officers entering the U.S. Navy were awarded a Reserve commission (commissioned as Ensign, USNR). Legislation was signed that all Reserve Officers on full-time Active Duty, previously designated by a "5" in the last digit of the designator, would be converted over to a Regular Navy commission by the close of Fiscal Year 2006.
Today, there is no distinction between USN and USNR Officers, no matter what the commissioning source. All hold the same ranks, have the same responsibilities and authority, and enjoy the same privileges. As part of the U.S. Navy's Active Reserve Integration (ARI) initiative that "operationalized" the Navy's Reserve Component, the term "U.S. Naval Reserve" was superseded by "U.S. Navy Reserve" and the term USNR was discontinued as a matter of Total Force policy in 2005. All officers in the U.S. Navy now use the term USN with their rank titles.
Unrestricted Line Officers (URL Officers) are commissioned Officers of the Line in the United States Navy who are qualified to Command at Sea the Navy's warfighting combatant units such as warships, submarines, aviation squadrons and SEAL Teams. They are also qualified to command the higher echelons of those units such as destroyer and submarine squadrons, aviation wings and groups, and special warfare groups. At the Flag Officer level, they also command carrier strike groups, expeditionary strike groups, task forces, and Fleet and Force commands. URL officers are also eligible to command shore installations, facilities and activities directly supporting the Navy's warfare mission.