What does the signal aspect that instructs to "stop, operate automatic stop, manual release" require an operator to observe?

The signal aspect instructing to "stop, operate automatic stop, manual release" requires the operator to ensure that the automatic stop arm lowers fully before proceeding. This requirement is crucial for the safety of train operations, as it indicates that the train must come to a complete stop and that the automatic stop mechanism has been engaged. Once the operator observes that the stop arm is fully lowered, they can then manually release the train to continue safely. This procedure helps maintain proper signaling protocols and ensures that the train does not move until it is safe to do so, preventing potential accidents or misunderstandings on the track. Observing this aspect is an essential part of maintaining operational integrity and following safety regulations.