This paper covers extensions to nonlinear editing for MPEG with emphasis on the representation of compositions, how they are created, edited, and played back. In order to emphasize the differences between JPEG intraframe compression and MPEG interframe capability, we limit the discussion to video. We discuss aspects of editing enabled by the JPEG compression standard. A brief description of MPEG follows with an explanation of the issues of editing and playing back MPEG compressed media. We extend the composition model (specifically the frame index in the media representation) to allow use of MPEG compressed media for editing and present a new hardware system which enables this capability. Next we explain the formatting of MPEG bitstreams and the transformation of arbitrary MPEG streams needed to accommodate edit and playback.