is then sent to the service secretary and the joint chiefs for review before it can be sent to the President, through the defense secretary, for consideration. The president nominates officers to be promoted from this list with the advice of the Secretary of Defense, the service secretary, and if applicable, the service's chief of staff or commandant. The President may nominate any eligible officer who is not on the recommended list if it serves in the interest of the nation, but this is uncommon. The Senate must then confirm the nominee by a majority vote before the officer can be promoted. Once confirmed, a nominee is promoted once he or she assumes an office that requires or allows an officer to hold that rank. For one-star or two-star positions of office that are reserved by statute, the President nominates an officer for appointment to fill that position. For the Navy and the Coast Guard, because the one-star and two-star grades are permanent ranks, the nominee may still be screened by an in-service promotion board to add their input on the nominee before the nomination can be sent to the Senate for approval. For the NOAA Commissioned Officer Corps and the Public Health Service Commissioned Corps, one-star and two-star rank are achieved by appointment from the President, or from their department secretary, and do not require senatorial approval. The standard tour length for most rear admiral positions is three years, but some are set at four or more years by statute. For the Navy, Coast Guard, and NOAA Corps, both grades of rear admiral are permanent ranks and do not expire when the officer vacates a one-star or two-star position. The Public Health Service Commissioned Corps, however, employs permanent promotions in both grades of rear admiral as well as position-linked temporary appointments in both grades (e.g., Assistant Surgeons General). Their temporary ranks expires when those officers vacate certain temporary positions of office designated to bear those ranks. Tradition By tradition in the United States Navy, when an officer is selected or appointed to flag rank, all current Navy flag officers write the selectee a letter congratulating him or her for attaining flag officer status. Retirement Other than voluntary retirement, statute sets a number of mandates for retirement. All one-star officers must retire after five years in grade or 30 years of service, whichever is later, unless they are selected or