Foreword This final draft European Telecommunication Standard (ETS) has been produced under the authority of the Joint Technical Committee (JTC) of the European Broadcasting Union (EBU) and the European Telecommunications Standards Institute (ETSI). This final draft ETS@based upon the EBU SPB 491 specification@ is not submitted for the Vote phase of the ETSI standards approval procedure. In view of the urgency for presenting the technical content of this proposed draft and for editorial reasons@ it is submitted for Vote in its original form as received from the EBU. NOTE: The EBU/ETSI Joint Technical Committee was established in 1990 to coordinate the drafting of European Telecommunication Standards in the specific field of radio@ television and data broadcasting. The European Broadcasting Union (EBU) is a professional association of broadcasting organisations whose work includes the coordination of its Members' activities in the technical@ legal@ programme-making and programme- exchange domains. The EBU has Active Members in about 50 countries in the European Broadcasting Area; its headquarters is in Geneva *. The European Telecommunication Standard embodied in the present document is the result of studies carried out. * European Broadcasting Union Case Postale 67 CH-1218 GRAND SACONNEX (Geneva) Switzerland Tel: +41 22 717 2111 FAX: +41 22 798 5897