cmLoopAction is a read-write enumeration controlling the lifecycle of a loopback test -- init to prepare it, start to begin running it, and stop to end it early. An administrator sequences these actions after configuring cmLoopInterface and cmLoopType to actually execute the diagnostic test. For example, an operator would set cmLoopAction to init(2) then start(3) to run a configured test, and could set it to stop(4) if they need to abort the test before it completes on its own.