\begin{thebibliography}{10}

\bibitem{rfc3428}
B.~Campbell, J.~Rosenberg, and H.~Schulzrinne, eds.,
  \htmladdnormallink{``Session initiation protocol {(SIP)} extension for
  instant messaging,''}{http://www.rfc-editor.org/rfc/rfc3428.txt} RFC 3428,
  Internet Engineering Task Force, Dec. 2002.

\bibitem{rfc2131}
R.~E. Droms, \htmladdnormallink{``Dynamic host configuration
  protocol,''}{http://www.rfc-editor.org/rfc/rfc2131.txt} RFC 2131, Internet
  Engineering Task Force, Mar. 1997.

\bibitem{draft-polk-dhcp-geo-loc-option}
J.~Polk {\em et~al.}, \htmladdnormallink{``{DHCP} option for geographic
  location,''}{http://www.ietf.org/internet-drafts/draft-polk-dhcp-geo-loc-opt%
ion-00.txt} internet draft, Internet Engineering Task Force, Oct. 2002.
\newblock Work in progress.

\bibitem{draft-schulzrinne-geopriv-dhcp-civil}
H.~Schulzrinne, \htmladdnormallink{``{DHCP} option for civil
  location,''}{http://www.ietf.org/internet-drafts/draft-schulzrinne-geopriv-d%
hcp-civil-00.txt} internet draft, Internet Engineering Task Force, Dec. 2002.
\newblock Work in progress.

\bibitem{rfc3046}
M.~Patrick, \htmladdnormallink{``{DHCP} relay agent information
  option,''}{http://www.rfc-editor.org/rfc/rfc3046.txt} RFC 3046, Internet
  Engineering Task Force, Jan. 2001.

\bibitem{draft-polk-geopriv-loc-object-semantics}
J.~Polk {\em et~al.}, \htmladdnormallink{``Semantics for {DHC} location object
  within
  {GEOPRIV},''}{http://www.ietf.org/internet-drafts/draft-polk-geopriv-loc-obj%
ect-semantics-00.txt} internet draft, Internet Engineering Task Force, Oct.
  2002.
\newblock Work in progress.

\bibitem{draft-garcia-sipping-3gpp-p-headers}
M.~Garcia, E.~Henrikson, and D.~L. Mills, \htmladdnormallink{``Private
  extensions (p-header) extensions to the session initiation protocol {(SIP)}
  for the 3rd-generation partnership project
  {(3GPP)},''}{http://www.ietf.org/internet-drafts/draft-garcia-sipping-3gpp-p%
-headers-02.txt} internet draft, Internet Engineering Task Force, Nov. 2002.
\newblock Work in progress.

\bibitem{rfc2142}
D.~H. Crocker, \htmladdnormallink{``Mailbox names for common services, roles
  and functions,''}{http://www.rfc-editor.org/rfc/rfc2142.txt} RFC 2142,
  Internet Engineering Task Force, May 1997.

\bibitem{rfc2822}
P.~Resnick, ed., \htmladdnormallink{``{Internet} message
  format,''}{http://www.rfc-editor.org/rfc/rfc2822.txt} RFC 2822, Internet
  Engineering Task Force, Apr. 2001.

\bibitem{rfc3281}
S.~Farrell and R.~Housley, \htmladdnormallink{``An {Internet} attribute
  certificate profile for
  authorization,''}{http://www.rfc-editor.org/rfc/rfc3281.txt} RFC 3281,
  Internet Engineering Task Force, Apr. 2002.

\end{thebibliography}
