There are numerous cases where units can be reduced to 0 MP or less, vehicles due to motive hits, vehicles due to extreme temperatures, Mechs due to leg actuator hits, and so on. When is a unit at 0 MP or less MP immobile?
1. Is a Mech reduced to 0 MP through the loss of leg actuators? For example, a 3/5 Atlas loses a foot actuator, lower leg actuator, and upper leg actuator, reducing it to 0/0.
2. Is a vehicle operating in extreme temperature reducing its MP to 0? For example a 2/3 Mars Assault Vehicle wanders into a desert at 70*C reducing it's movement to 0/0.
3. Is a vehicle that takes additional MP reductions while at 0 MP be reduced to less than 0 MP and is it considered immobile at that point? For example, a very unlucky Mars Assault Tank receives motive hits with many roll results of 8-9 (-1 cruise MP/each) reducing it to 0 MP and then trying to reduce it below 0 MP in successive phases and turns.
4. Is a landed VTOL with 0 MP (presumably after many rotor hits)?