Definition 3. A Multimedia data stream (MMDS) is a data stream (as defined above) that contains at least one Micon as one of its attributes, according to a certain schema.

Definition 4. A Continuous Query (CQ) is a query registered by a user at the MMDSMS that is to be executed - theoretically - forever. If the CQ includes one or more multimedia operators such as transformation or fusion operators then the CQ is called a multimedia CQ, or m-CQ for short.