A duty shift was a moment of the workday in starship duty where crewmen were effectively working. The officer in charge of the bridge during a shift was often referred to as the shift officer when the commanding officer was not on the bridge. Three-shift rotations were common in Starfleet, as well as in the Tal Prai'ex. It was common for shift officers, in the Tal Prai'ex, to take command of the ship in battle if they had to fight while on duty.(RIS Bouteina et al.)