Title 49
SECTION 236.756
236.756 Lock, bolt.
§ 236.756 Lock, bolt.A mechanical lock so arranged that if a switch, derail or movable-point frog is not in the proper position for a train movement, the signal governing that movement cannot display an aspect to proceed; and that will prevent a movement of the switch, derail or movable-point frog unless the signal displays its most restrictive aspect.