Berth
Also: signal berth, td berth
A stretch of track on a signaller’s screen, usually the one leading up to a signal, which holds the headcode of the train in it.
Example
Made-up berth numbers.
A signaller’s screen shows the track as a diagram, split into berths. Each berth is a little box that shows the headcode of the train standing in or approaching it.
Berths have four-character IDs, and they belong to a signalling area. As a train moves along, its headcode steps from berth to berth.