If a monster walks towards a door track pursuing a target, it may become stuck on the door track until the direction towards its target changes significantly. If a monster is pushed onto a ledge by being attacked, or is standing on the threshold of a lift which begins to ascend, it may become trapped on the edge of the raised sector. The monster cannot normally turn, fire a weapon, or use projectile attacks in this situation (melee attacks, if any, are sometimes available). Lowering the lift a second time, or attacking the monster again so that it falls off the ledge entirely, releases it from its confined state.