What is not a condition for the absence of a Trip ID?

The absence of a Trip ID is associated mainly with the operational modes of a train. Trip IDs are used in various train control systems to identify specific trips and their associated parameters, such as schedules and routes.

In the context of the given options, when a train is moving at speed, it typically operates under control systems that rely heavily on Trip IDs for safe navigation and operation. Therefore, speed is directly related to the operational state of the train, which usually requires a valid Trip ID to function safely and adhere to the scheduling system.

On the other hand, modes like Yard mode and Release mode, as well as occurrences in Non-CBTC (Communications-Based Train Control) territories, present conditions where Trip IDs may not be necessary or relevant. For example, in Yard mode, trains are moving in a confined area where manual control is often applied. Release mode could indicate a situation where the automatic control is temporarily disabled, and in Non-CBTC territories, there's a potential absence of advanced tracking systems that utilize Trip IDs.

Thus, considering these operational contexts, the state of a train moving at speed inherently requires a Trip ID for operational integrity, making it the option that does not exemplify a condition for the absence of a Trip ID.