What must be confirmed about signals before authorizing a train's movement against traffic?

Before authorizing a train's movement against traffic, it is crucial to confirm that the signals are in the Stop position. This is essential for safety reasons; the Stop signal indicates that the track ahead is not clear or that there are potentially hazardous conditions. If the signals were not in the Stop position, it could imply that it is safe for a train to proceed, which would be contrary to the requirement of having trains move against the flow of traffic. Ensuring that signals are confirmed in the Stop position provides a necessary layer of safety and allows dispatchers to manage train movements effectively while minimizing the risk of accidents or collisions.

The other options do not hold up against the critical safety priorities involved in train dispatching. Clear signals would suggest that movement against traffic could be authorized, which is not safe when considering the potential for conflicting movements. Signals being in a flashing mode might indicate an intermediate condition that does not clearly convey whether it is safe to proceed against traffic. Lastly, while it is important for the engineer to be aware of the situation, the dispatcher is responsible for confirming the signal indications themselves before authorizing movement.