This notification is sent to the manager whenever a line's status or relay changes, carrying the affected slot (relaySlot), port (relayPort), and the new status (relayStatus) as its parameters. Admins rely on this trap to be alerted in near-real time whenever a relay flips between normal and closed, rather than having to poll the relayTable continuously. For example, receiving this trap with relayStatus set to closed for Slot-2/Port-5 would immediately tell an admin that line just entered closed-loop test mode, whether intentionally or due to a fault.