The ITU Radiocommunication Assembly considering: a) that signal processing in the HDTV studio environment is in a digital form; b) that the source bit rate of a HDTV digital studio signal is in excess of 1 Gbit/s; c) that equipment interconnections in a serial digital format are used within HDTV studio complexes; d) that bit-rate reduction is commonly used in the production chain of HDTV programmes; e) that bit-rate reduction will be applied to video signals at several places along the HDTV chain that extends from the production of programmes to their final delivery; f) that it is essential that any video artefacts due to the combined effect of such bit-rate reduction processes be statistically kept below the level of perceptibility up to the end of the HDTV chain.