Specifies the system layer of the coding. It was developed principally to support the combination of the video and audio coding methods defined in ISO/IEC 13818-2 and ISO/IEC 13818-3 (published in South Africa as identical adoptions under the designations SANS 13818-2 and SANS 13818-3). The system layer supports six basic functions: the synchronization of multiple compressed streams on decoding; the interleaving of multiple compressed streams into a single stream; the initialization of buffering for decoding start up; continuous buffer management; time identification; multiplexing and signalling of various components in a system stream.