In terms of signal passing, which of the following signals is valid for a train to go past?

In the context of train signaling systems, specific signal numbers correspond to particular instructions for train movement. The value of 279 indicates a proceed signal that permits a train to pass a particular signal safely. This value aligns with established codes that signal engineers use to communicate readiness for a train to continue its journey, ensuring that the train can proceed without encountering hazards on the track ahead.

The other signal values, although relevant in different contexts, do not represent a valid permission for a train to go past in the same manner as 279 does. Each signal number has defined meanings, so understanding these distinctions is critical for safe train operations.