Network Working Group J. Postel Request for Comments: 861 J. Reynolds ISI Obsoletes: NIC 16239 May 1983
TELNET EXTENDED OPTIONS - LIST OPTION
This RFCspecifies a standard for the ARPA Internet community. Hosts on the ARPA Internet are eXPected to adopt and implement this standard.
1. Command Name and Code
EXTENDED-OPTIONS-LIST (EXOPL) 255
2. Command Meanings
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 section 5 below.
3. Default
WON'T EXOPL, DON'T EXOPL
RFC861 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).
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
