This counts Change of Authorization requests the gateway has received, each one an instruction to change a subscriber's authorization (such as bandwidth cap or QoS profile) mid-session without disconnecting them. Because CoA lets an operator push a policy change live without kicking the subscriber offline, this counter tells an admin how often such changes are being applied to sessions on this gateway, for instance from a data-cap enforcement engine. A mobile operator's policy server throttling a subscriber who hit their monthly data cap would increment this counter once for that throttle event.