This is a list of naval officer designators in the United States Navy. In the United States Navy, all active and reserve component officers are assigned to one of four officer 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 designator. Definition The officer billet designator codes are four-digit numbers used to identify the primary naval specialty qualifications required of the billet incumbent and to administratively categorize officer billets for proper management and identification. They serve as a manpower management tool when used in conjunction with the officer designator codes. These codes are entered in the Manpower Authorizations (OPNAV Form 1000/2) to indicate the categories of officers required for the billets. The first digit identifies the officer's community. The second and third digits denote the officer's area of specialization within the line, staff corps, LDO, or warrant officer community. The final (fourth) digit denotes the officer's current type of commission. Between fiscal year 1992 and fiscal year 2005, all officers entering the U.S. Navy were awarded a Reserve commission (commissioned as ensigns, 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 to a regular Navy commission by the close of fiscal year 2006. 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Integration (ARI) initiative that "operationalized" the Navy's Reserve component, the term "U.S. Naval Reserve" was superseded by "U.S. Navy Reserve", and the term USNR was discontinued as a matter of Total Force policy in 2005.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. As used above, Full Time Support (FTS) program officers are reserve officers serving on either fixed or indefinite periods of active duty, while remaining reserve officers, under the authority of 10 USC 12310. The Full Time Support program exists to provide FTS for training, administration, recruiting, organization, and equipping the reserve components. (1xxx) Line Officers Fully Warfare