This read-write integer is set by an admin to trigger a snapshot of the current active IP accounting table into the separate checkpoint accounting table. Admins use it to freeze a point-in-time copy of traffic statistics for later comparison or reporting without disturbing the live, still-accumulating accounting table. For example, an admin might set this flag at the end of a billing period to capture that period's traffic counts into the checkpoint table before the live table continues collecting new data.