cmStateLastChange is a read-only TimeTicks value recording the system uptime at the moment a resource's cmStateOperState last changed. An administrator uses it to determine how recently a given board, port, or link flipped state, helping correlate a service issue with a specific event in time. For example, if a subscriber's outage began at a known time, the operator can check whether the affected line's cmStateLastChange lines up with that same uptime value to confirm the state flap caused the outage.