What prefixes are used in the Book of Rules and what do they indicate?

The prefixes used in the Book of Rules serve to provide clarity on the operational context of train movements. Specifically, the prefix "S" stands for single track, indicating that the train will be operating on tracks that may not allow for two-way traffic. This is crucial for ensuring that train crews are aware of the limitations of the track they are on, which helps prevent collisions and promotes safety.

The prefix "D," on the other hand, signifies two or more tracks, implying that there are multiple parallel tracks available. This information is vital for operational efficiency, as it allows for smoother traffic flow and better coordination between trains running in both directions.

Understanding these prefixes is essential for train crews as they navigate the operational landscape and make decisions based on track availability and safety protocols. This knowledge aids in maintaining the flow of train operations and ensures compliance with safety standards.