In automatic block territory where Rule 251 is in effect, what is needed for a train to make a reverse movement within the limits of the block?

In automatic block territory where Rule 251 is in effect, the requirement for a train to make a reverse movement within the limits of the block is that it must receive Form-L authorization. This is a crucial procedure because Rule 251 governs the control and movements of trains to ensure safety when operating under conditions where signal indications may restrict or allow certain movements.

Form-L serves as formal documentation that outlines the conditions and authorizations for specific movements, particularly for reverse operations that may not typically be covered by standard signaling practices. It ensures all parties involved are aware of the maneuver, thereby minimizing risks associated with such movements in an area that regularly operates under rules designed to maintain separation between trains.

While dispatcher's verbal approval, a signal from the engineer, or written permission from the conductor may play roles in various operational scenarios, they do not constitute the formalized and documented authorization specified for reverse movements in Rule 251 territory. Therefore, Form-L authorization is essential to maintain proper communication, adherence to safety protocols, and operational integrity within the block's confines.