a SIRI Notification Producer mediates the flow of notifications it processes so as to reduce the amount of data traffic to a subscriber. All SIRI subscriptions for a Subscriber are automatically assigned to a Subscriber Channel. The subscriptions in a channel are mediated collectively; if a Situation affects more than one subscription within a channel, only a single notification is sent to the subscriber. The resulting delivery contains all updates for all subscriptions in the channel. There is at least one subscriber channel per Subscriber; some implementations may allow more than one channel for a given subscriber.