What is the effect of the drum switch being in the "Advance" position on the rear of the train?

When the drum switch is in the "Advance" position on the rear of the train, the system is designed so that it indicates to the head operating car that the train is in a forward direction, which would typically allow for the advanced control of train operations. However, in this situation, the specific effect is that the head operating car does not receive the Automatic Directional Control Logic (ADCL) indication.

This lack of indication has operational significance, as it may affect the ability to monitor and control the train consistently across its length, especially if there's an expectation for directional signals to be uniform. Understanding the implications of the drum switch position is critical for train engineers to ensure proper communication and operational safety throughout the train's journey.