Warrant officer
In the Singapore Armed Forces, warrant officers begin as third warrant officers (3WO), previously starting at the rank of second warrant officer, abbreviated differently as WO2 instead. This rank is given to former specialists who have attained the rank of master sergeant and have either gone through, or are about to go through the Warfighter Course at the Specialist and Warrant Officer Advanced School (SWAS) in the Specialist and Warrant Officer Institute (SWI). In order to be promoted to a second warrant officer (2WO) and above, they must have been selected for and graduated from the joint warrant officer course at the SAF Warrant Officer School. Warrant officers rank between specialists and commissioned officers. They ordinarily serve as battalion or brigade regimental sergeant majors. Many of them serve as instructors and subject-matter experts in various training establishments. Warrant officers are also seen on the various staffs headed by the respective specialist officers. There are six grades of warrant officer (3WO, 2WO, 1WO, MWO, SWO &amp; CWO).