Telnet Extended Options: List Option

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INTERNET STANDARD

Network Working Group                                          J. Postel
Request for Comments: 861                                    J. Reynolds
                                                                     ISI
Obsoletes: NIC 16239                                            May 1983

                 <span class="h1">TELNET EXTENDED OPTIONS - LIST OPTION</span>


This RFC specifies a standard for the ARPA Internet community.  Hosts on
the ARPA Internet are expected to adopt and implement this standard.

<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>.  Command Name and Code</span>

   EXTENDED-OPTIONS-LIST (EXOPL)     255

<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>.  Command Meanings</span>

   IAC DO EXOPL

      The sender of this command REQUESTS that the receiver of this
      command begin negotiating, or confirms that the receiver of this
      command is expected to begin negotiating, TELNET options which are
      on the "Extended Options List".

   IAC WILL EXOPL

      The sender of this command requests permission to begin
      negotiating, or confirms that it will begin negotiating, TELNET
      options which are on the "Extended Options List".

   IAC WON'T EXOPL

      The sender of this command REFUSES to negotiate, or to continue
      negotiating, options on the "Extended Options List".

   IAC DON'T EXOPL

      The sender of this command DEMANDS that the receiver conduct no
      further negotiation of options on the "Extended Options List".

   IAC SB EXOPL <subcommand>

      The subcommand contains information required for the negotiation
      of an option of the "Extended Options List".  The format of the
      subcommand is discussed in <a href="#section-5">section 5</a> below.

<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>.  Default</span>

   WON'T EXOPL, DON'T EXOPL




<span class="grey">Postel & Reynolds                                               [Page 1]</span>

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<span id="page-2" ></span>
<span class="grey"><a href="./rfc861">RFC 861</a>                                                         May 1983</span>


      Negotiation of options on the "Extended Options List" is not
      permitted.


<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>.  Motivation for the Option</span>

   Eventually, a 257th TELNET option will be needed.  This option will
   extend the option list for another 256 options in a manner which is
   easy to implement.  The option is proposed now, rather than later
   (probably much later), in order to reserve the option number (255).

<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>.  An Abstract Description of the Option</span>

   The EXOPL option has five subcommand codes:  WILL, WON'T, DO, DON'T,
   and SB.  They have exactly the same meanings as the TELNET commands
   with the same names, and are used in exactly the same way.  For
   consistency, these subcommand codes will have the same values as the
   TELNET command codes (250-254).  Thus, the format for negotiating a
   specific option on the "Extended Options List" (once both parties
   have agreed to use it) is:

      IAC SB EXOPL DO/DON'T/WILL/WON'T/<option code> IAC SE

   Once both sides have agreed to use the specific option specified by
   <option code>, subnegotiation may be required.  In this case the
   format to be used is:

      IAC SB EXOPL SB <option code> <parameters> SE IAC SE





















Postel & Reynolds                                               [Page 2]