MCStacker/tips/en/shulker_bullet.Target.txt

The target of the bullet can be set by entering the TargetL or TargetM (these are the target UUID's Least and Most). Alternatively you can enter the target's coordinates. TargetX, TargetY and TargetZ. If all five values are set, MCStacker will ignore the TargetX, TargetY and TargetZ values.