RFC 861 (rfc861) - Page 2 of 2

Telnet Extended Options: List Option

RFC 861                                                         May 1983


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


4.  Motivation for the Option

   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).

5.  An Abstract Description of the Option

   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/