\begin{thebibliography}{1}

\bibitem{draft-ietf-impp-cpim-pidf}
H.~Sugano, S.~Fujimoto, {\em et~al.}, \htmladdnormallink{``Presence information
  data format
  {(PIDF)},''}{http://www.ietf.org/internet-drafts/draft-ietf-impp-cpim-pidf-0%
8.txt} internet draft, Internet Engineering Task Force, May 2003.
\newblock Work in progress.

\bibitem{rfc2327}
M.~Handley and V.~Jacobson, \htmladdnormallink{``{SDP:} session description
  protocol,''}{http://www.rfc-editor.org/rfc/rfc2327.txt} RFC 2327, Internet
  Engineering Task Force, Apr. 1998.

\bibitem{rfc3264}
J.~Rosenberg and H.~Schulzrinne, \htmladdnormallink{``An offer/answer model
  with session description protocol
  {(SDP)},''}{http://www.rfc-editor.org/rfc/rfc3264.txt} RFC 3264, Internet
  Engineering Task Force, June 2002.

\bibitem{rfc2778}
M.~Day, J.~Rosenberg, and H.~Sugano, \htmladdnormallink{``A model for presence
  and instant messaging,''}{http://www.rfc-editor.org/rfc/rfc2778.txt} RFC
  2778, Internet Engineering Task Force, Feb. 2000.

\bibitem{rfc2119}
S.~Bradner, \htmladdnormallink{``Key words for use in {RFCs} to indicate
  requirement levels,''}{http://www.rfc-editor.org/rfc/rfc2119.txt} RFC 2119,
  Internet Engineering Task Force, Mar. 1997.

\bibitem{rfc2141}
R.~Moats, \htmladdnormallink{``{URN}
  syntax,''}{http://www.rfc-editor.org/rfc/rfc2141.txt} RFC 2141, Internet
  Engineering Task Force, May 1997.

\bibitem{rfc2648}
R.~Moats, \htmladdnormallink{``A {URN} namespace for {IETF}
  documents,''}{http://www.rfc-editor.org/rfc/rfc2648.txt} RFC 2648, Internet
  Engineering Task Force, Aug. 1999.

\bibitem{draft-mealling-iana-xmlns-registry}
M.~Mealling, \htmladdnormallink{``The {IETF} {XML}
  registry,''}{http://www.ietf.org/internet-drafts/draft-mealling-iana-xmlns-r%
egistry-05.txt} internet draft, Internet Engineering Task Force, June 2003.
\newblock Work in progress.

\bibitem{draft-ietf-simple-presence}
J.~Rosenberg, \htmladdnormallink{``A presence event package for the session
  initiation protocol
  {(SIP)},''}{http://www.ietf.org/internet-drafts/draft-ietf-simple-presence-1%
0.txt} internet draft, Internet Engineering Task Force, Jan. 2003.
\newblock Work in progress.

\end{thebibliography}
