\section*{Changes in Version -06}

Since version -05, the following changes have been made. 

\begin{itemize}
\item Definition of call leg added.

\item Clarified definition of transaction and relation to {\ACK} (since
{\ACK} is not really part of the transaction, even though it has the
same \header{CSeq} and \header{Call-ID}).

\item Postscript version had old proxy and redirect drawing.

\item Vestiges of URL short form removed.

\item Clarified that clients of all sorts (user agent, proxy) {\MAY}
issue {\CANCEL}.

\item \header{CSeq} reduced to 32 bits for implementation convenience.

\item Bug fixes in {\tt process\_request} code.

\item Moved ``Queued'' response to main spec, since the decision to
queue can (will typically) also be taken by the callee, rather than just
the caller. This does not complicate the client or server behavior.

\item \header{ETag} removed in favor of the \header{tag} parameter in
the URI.

\end{itemize}
