for this requirement is tagging up. If the runner retouches the origin base at any time after the fly ball is first touched by a fielder, he may attempt to advance to the next base or bases at his own risk. The penalty for failing to retouch (if the defensive team notices this) is that the advancing runner can be put out on a live appeal in which the defensive team player with the ball touches the base from which that runner departed prematurely. If a runner tagged up and tries to run to the next base in sequence, they are deemed out if tagged by an infielder at any point before reaching the base or the ball arrives at the base ahead of the runner. However, if the runner is not forced to run to the next base in sequence, they are not deemed out until they are tagged. This often leads to a runner being trapped between two or more infielders trying to tag them before reaching any base: a situation known as being "caught in no-man's-land". Only one runner may occupy a base at a time; if two runners are touching a base at once, the trailing runner is in jeopardy and will be out if tagged. However, if the trail runner reached the base having been forced there, it is the lead runner who will be out when tagged for failing to reach his force base. Either such occurrence is very rare. Thus, after a play, at most three runners may be on the basepaths, one on each base—first, second, and third. When three runners are on base, this is called bases loaded. Baserunners may attempt to advance, or steal a base, while the pitcher is preparing to make a pitch, while he is making a pitch, or while waiting for a return throw from the catcher after a pitch. The pitcher, in lieu of delivering the pitch, may try to prevent this by throwing the ball to one of the infielders in order to tag the runner; if successful, it is called a pick-off. He may also, as part of a planned sequence, throw a pitch well outside and high of the strike zone to his catcher who is waiting for it upright there, and is thus better prepared to throw out a runner trying to steal; this sequence is called a "pitchout." If the