What is required for a train to occupy the main track between specific points as per track permits?

A track permit issued by a designated control operator is essential for a train to occupy the main track between specific points. This process ensures that all necessary safety precautions and operational protocols are followed, effectively coordinating train movements on the network. The track permit serves as official authorization that confirms the allotted sections of the main track are clear of conflicting trains, allowing the authorized train to proceed safely without risking collisions or accidents.

Additionally, this system guarantees that the control operator can monitor and manage the occupancy of the main track, ensuring that it is used safely and efficiently. Other forms of authorization or verification, such as those suggested by the other options, do not provide the formalized, centralized command necessary for safe train operations on the main track.