This indicates whether SCTP's optional heartbeat mechanism is actively probing a specific remote destination address for this association, as opposed to cSctpAssocRemAddressStatus which reports the reachability result of that probing. It matters because heartbeats are what let SCTP detect a failed idle path before data even needs to be sent on it, so a secondary (backup) path with heartbeats disabled here won't have its failure detected until an actual attempt to use it fails. An admin relying on fast multihoming failover to a backup address should confirm this reads active for that backup address, not just for the primary path.