When holding the position of first sergeant, while uncommon, the master sergeant is referred to as "first sergeant"; however, when not in the position of first sergeant, master sergeants are addressed as "sergeant". This is the standard address for all pay grades E-5 through E-8. Use of the term "top" or "master sergeant" is not a requirement, but is considered courteous, and remains to be at the discretion of the one addressing the master sergeant, though "top" is preferred, due to the long tradition of its use in the US Army, which has, since the Civil War, emphasized the importance of senior NCOs closely advising and instructing newly-commissioned second lieutenants.