In the United States Navy, commissioned officers are either line officers or staff corps officers. Those of the Staff Corps are specialists in career fields which are professions unto themselves, such as scientists, physicians, 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. On Winter Blue and khaki uniforms, the specialty insignia is a collar device worn on the left collar, while the rank device is worn on the right.See explanation of staff and line functions.
†An officer designator describes their general community or profession. The (fourth) digit (X) denotes the whether the officer has a Regular (0), Reserve (5), or Full Time Support (7) commission.
Staff corps officers are specialists in certain areas, such as supply and medicine. They wear staff corps insignia. A doctor can become the commanding officer (CO) of a hospital, a hospital ship, or a medical school or the chief of the Bureau of Medicine. A supply officer can become the CO of a supply depot or a school or the head of the Navy Supply Systems Command. When officers are of the same grade and date of commissioning, but from different officer’s categories, seniority takes precedence in the following order:
Judge Advocate General
In addition to regular commissioned officers, the Navy has another group of officers called commissioned warrant officers.