This is the per-instance (i.e., per specific attachment of the rule's parent profile to a specific interface/direction) version of the packet counter, distinct from the aggregate cienaCesAclGlobalRuleStatsPacketCount which sums matches across every attachment of that rule's profile device-wide. An admin needs this instance-level granularity specifically when the same named profile is attached to multiple interfaces, to determine which particular attachment is actually seeing the matching traffic rather than just knowing the rule matches something somewhere on the device. For example, if a profile containing this rule is attached to five different interfaces, this instance-level counter lets an admin identify that the matches are concentrated on just one of those five attachments rather than spread evenly, focusing further investigation there.