The X-Receding-PlaylistChange header is defined only for use in an Announce (section 126.96.36.199) request sent to a client. The header indicates that the playlist entry described by the SDP in the Announce request is the previous entry in the server-side playlist.
The server MUST NOT send this header unless it was rewinding the content (that is, streaming the content backward) and sent the Announce request as a result of reaching the beginning of the playlist entry.
The syntax of the X-Receding-PlaylistChange header is as follows:
X-Receding-PlaylistChange = "X-Receding-PlaylistChange: 1"