<P> Note 2: See also Commodore (United States)--today an honorific title (but not a pay grade) for selected URL captains (O - 6) in major command of multiple subordinate operational units, and formerly a rank (O - 7). </P> <P> Note 3: The term "line officer of the naval service" includes line officers of both the Navy and the Marine Corps . All U.S. Marine Corps officers are considered "of the line," including Marine Corps limited duty officers, chief warrant officers, and warrant officers, regardless of grade or specialty . </P> <P> The Act of Congress of March 4, 1925, provided for Navy, Marine Corps, and Coast Guard officers to be promoted one grade upon retirement, if they had been specially commended for performance of duty in actual combat . Combat citation promotions were sometimes called "tombstone promotions" by disgruntled officers who did not qualify for them, but the term was not used by the recipients . These promotions conferred all the perks and prestige of the higher rank, including the loftier title, but no additional retirement pay . The Act of Congress of February 23, 1942, enabled promotions to three - and four - star grades . Tombstone promotions were subsequently restricted to citations issued before January 1, 1947, and finally eliminated altogether effective November 1, 1959 . The practice was terminated as part of an effort to encourage senior officer retirements prior to the effective date of the change to relieve an over-strength in the senior ranks . </P> <P> Any officer who served honorably in a grade while on active duty receives precedence on the retirement list over any "tombstone officer" holding the same retired grade . Tombstone officers ranked among each other according to their dates of rank in their highest active duty grade . </P>

What are the levels of rank in the navy