A CSM, BSM or SSM is generally addressed as "Sergeant Major". However, a cavalry SSM is often addressed as "Mr (surname)" by officers, and as "Sir" or "Mr (surname), Sir" by his inferiors, with the salutation "Sergeant Major" being reserved for Staff Sergeants. Typically for the British Army, protocol can vary widely between units, creating a minefield for outsiders, new recruits, and soldiers serving outside their parent regiments.
In particular, the Regimental SergeantMajor (RSM) (WO1) is the senior WO of a battalion or regiment, equivalent to a Command SergeantMajor in the United States.
Marine Corps SergeantsMajor serve as the senior enlisted Marine in the Corps' units of battalion, squadron or higher echelon, to assist the unit's commander and to handle matters of discipline and morale among the enlisted Marines.
The full title of sergeantmajor fell out of use until the latter part of the 18th century, when it began to be applied to the senior non-commissioned officer of an infantry battalion or cavalry regiment.
Company SergeantMajor (CSM) is an appointment held by Warrant Officers Class 2 (WO2) in the British Army and Royal Marines, and also in other armies of the Commonwealth; in the Canadian Forces, this appointment is held by a Master Warrant Officer (MWO).
BatterySergeantMajor (BSM) is the equivalent in the Royal Artillery and Royal Regiment of Canadian Artillery.
A CSM, BSM or SSM is generally addressed as "SergeantMajor" (or often as "Sir" or "Ma'am" by subordinates).