\section{Changes}

Since draft03 (July 30, 1997 version) of RTSP, the following changes were made:

\begin{itemize}

\item PEP was removed, ``Require'' header returns

\item Usage of SDP within RTSP is specified as an appendix

\item Minimal RTSP implementation specified as an appendix

\end{itemize}

Between draft02 (March, 1997) and draft03 (July, 1997), the following
changes were made:

\begin{itemize}
\item Definition of RTP behavior.

\item Definition of behavior for container files.

\item Remove server-to-client DESCRIBE request.

\item Allowing the {\sf Transport} header to direct media streams to
unicast and multicast addresses, with an appropriate warning about
denial-of-service attacks.

\item Add {\sf mode} parameter to {\sf Transport} header to allow
RECORD or PLAY.

\item The {\sf Embedded binary data} section was modified to clearly 
indicate the stream the data corresponds to, and a reference to the 
Transport header was added.

\item The {\sf Transport} header format has been changed to use
a more general means to specify data channel and  application
level protocol. It also conveys the port to be used at the server for RTCP
messages, and the start sequence number that will be used in the RTP packets.

\item The use of the Session: header has been enhanced. Requests for multiple
URLs may be sent in a single session.

\item There is a distinction between aggregate(presentation) URLs and stream
URLs. Error codes have been added to reflect the fact that some methods may be
allowed only on a particular type of URL.

\item Example showing the use of aggregate/presentation control using a single RTSP session has been added.

\item Support for the PEP(Protocol Extension Protocol) headers has been added.

\item Server-Client DESCRIBE messages have been renamed to ANNOUNCE for better
clarity and differentiation.

\end{itemize}
Note that this list does not reflect minor changes in wording or correction of
typographical errors.

