What governs the operation of a train within interlocking limits in CSS territory?

The operation of a train within interlocking limits in Centralized Traffic Control (CTC) or CSS (Centralized Supervisory System) territory is primarily governed by interlocking signal indications. Interlocking signals are specifically designed to control train movements to ensure safe operation through complex track layouts, preventing conflicting movements and ensuring that trains are routed safely.

Interlocking signals indicate whether a train can proceed, and they provide information regarding track occupancy and switch positions. These signals are crucial for maintaining safety and order on the rail network, especially in areas where multiple tracks converge or where complex maneuvers are required.

The other options do not adequately address the established safety protocols and operational standards in interlocking limits. Distance indicators, for instance, serve a different purpose by informing engineers of the distance to the next signal, but they do not govern train operations directly within interlocking limits. Verbal orders from the Dispatcher and written instructions at a station may provide critical information and directives, but signals remain the primary governing mechanism for ensuring safe and efficient train movements within interlocking areas.