This Recommendation supports the splicing of MPEG-2 streams for the purpose of digital program insertion, which includes advertisement insertion and insertion of other content types. An in-stream messaging mechanism is defined to signal splicing and insertion opportunities and it is not intended to ensure seamless splicing. As such, this Recommendation does not specify the splicing method used or constraints applied to the streams being spliced, nor does it address constraints placed on splicing devices. This Recommendation also supports accurate signalling of events in the stream.