This read-only Counter64 counts the total IGMP leave messages received on this PM instance. Comparing Leaves against Joins over the same bin shows whether multicast group membership on this port is growing or churning, which matters for capacity planning on a video-heavy access node; because it is drawn from the most recently completed short-interval historical bin, it is a closed record of the interval right before the current one, useful for checking whether a problem seen right now had already started in the previous window. On an access port serving a multi-dwelling unit, a count of 1,172 over the last completed collection window is the kind of number an admin would trend against the join/leave rate on the same port to judge whether it's normal channel-surfing or an anomaly worth a closer look.