ZEDs with dismembered limbs cannot play knockdown / getup animations. Knocked down ZED will die instantly if it will fall from the height greater than 7.5 meters. Up to 25 checks (due to code specifics - actually 32) with 0.2s intervals between each two allowed before ZED will be forced to get up back on feet, this results in overall maximum knockdown time of 6.4 seconds. Once fell on the ground, ZED will be evaluating its getup possibilities within 0.2 second intervals, ZEDs with velocity greater than 100 uu/s or whose rigid body is still awake and simulated should skip getup animation untill their next evaluation check. By any means only 5 ZEDs are allowed to be knocked down at time (this rule, however, implies 5 separate instances of knockdown - each ZED can be knocked down individually only if in the world there are less than 5 already knocked ZEDs, otherwise it is possible to knockdown much bigger groups of ZEDs, for example with the single explosion). Knockdown is a special move where ZED goes into 'ragdoll' state.