I can confirm that ! the rxm rx rym and ry does also not work ! --> testfor @e[type=Zombie,rx=20,rxm=-20,ry=20,rym=-20]
I can confirm that ! the rxm rx rym and ry does also not work ! --> testfor @e[type=Zombie,rx=20,rxm=-20,ry=20,rym=-20]