The ITU Radiocommunication Assembly considering a) that the broadcasting with a single transmitter of information supplementary to the sound programmes is technically feasible, particularly through the use of digital signals modulating a sub-carrier; b) that the use of many types of supplementary information for various applications can be foreseen; c) that the transmission of such information with no direct relationship to the main programme can be accomplished by such techniques; d) that it is desirable to encourage development of compatible or possibly common systems; e) that Recommendation ITU-R BS.643 specifies a “system for automating tuning and other applications in FM radio receivers for use with the pilot tone system”.