What does a green square indicate on the active PA-5 cab display?

A green square on the active PA-5 cab display signifies normal operation of the train's systems. This indicates that all systems are functioning as expected without any faults or errors. The green color typically conveys a status of readiness and reliability, allowing the engineer to proceed confidently in a safe operating environment.

In operational contexts, such indicators are crucial for quickly interpreting the status of train systems. When the display shows a green square, it confirms that the train is not in a fault state, thus allowing the engineer to focus on other operational tasks without concern for immediate issues in the train's systems. Understanding these indicators helps train engineers maintain safety and efficiency in their operations.