ISO/IEC 13818-1:2013 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. The system layer supports six basic functions: 1) the synchronization of multiple compressed streams on decoding; 2) the interleaving of multiple compressed streams into a single stream; 3) the initialization of buffering for decoding start up; 4) continuous buffer management; 5) time identification; 6) multiplexing and signalling of various components in a system stream.