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 24-hour bin, frozen once the day rolled over, it is frozen and safe to use for day-over-day comparison, since no further traffic will ever be added to it. On a subscriber-facing IPTV access port, a count of 2,075 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.