RFC 1053 (rfc1053) - Page 2 of 21
Telnet X
Alternative Format: Original Text Document
RFC 1053 Telnet X.3 PAD Option April 1988 ("DO") or the user ("WILL") side. Once DO and WILL have been exchanged, the host ("DO") telnet may send the following messages: IAC SB X.3-PAD SET... IAC SE IAC SB X.3-PAD RESPONSE-SET ... IAC SE IAC SB X.3-PAD SEND IAC SE while the user ("WILL") telnet may send the following messages: IAC SB X.3-PAD IS ... IAC SE IAC SB X.3-PAD RESPONSE-IS ... IAC SE The code for SET is 0 The code for RESPONSE-SET is 1 The code for IS is 2 The code for RESPONSE-IS is 3 The code for SEND is 4 Messages listing parameter-value pairs may contain any number of such pairs, including zero. Each parameter and each value occupies one octet, except that 255 (IAC) is doubled wherever it appears. 3. Default conditions The initial state is DON'T X.3-PAD, WON'T X.3-PAD. This RFC does not specify default values for most X.3 parameters. If the host telnet wishes a particular initial state (as it normally will), it should negotiate for it after exchange of DO/WILL messages. X.3-PAD parameter values need not be preserved except when DO/WILL X.3-PAD is in effect. Thus if a host enables ("DO") X.3-PAD, negotiates about some parameters, then for some reason disables ("DONT") and later re-enables X.3-PAD, it must renegotiate any parameters it cares about. Keeping in mind that the host telnet may not recognize all the parameters known to the user telnet, it is suggested that the user telnet's initial parameters allow a reasonable level of service even if they are never changed (e.g., it would be unwise to begin with all data forwarding conditions disabled). Extensions to X.3 should default to states resembling normal X.3 service where possible. Levy & Jacobson
