Modifications to the TELNET Specification
A final set of changes to the new Telnet specifications before the planned switchover.
McKenzie, A.M., "Modifications to the TELNET Specification", RFC 562, DOI 10.17487/RFC0562, August 1973, <https://www.rfc-editor.org/info/rfc562>.
@misc{rfc562,
series = {Request for Comments},
number = 562,
howpublished = {RFC 562},
publisher = {RFC Editor},
doi = {10.17487/RFC0562},
url = {https://www.rfc-editor.org/info/rfc562},
author = {A.M. McKenzie},
title = {{Modifications to the TELNET Specification}},
pagetotal = 2,
year = 1973,
month = aug,
} RFC text
Network Working Group A. McKenzie Request for Comments: 562 BBN-TENEX NIC: 18638 28 August 1973 Updates: RFC 495 References: RFCs 513, 529 Modifications to the TELNET Specification Almost four months have passed since the new TELNET Protocol specification was published. Since then, only two RFCs have been issued suggesting modifications, and the most recent of these was distributed two months ago. Further, the date from the old TELNET to the new TELNET (1 January 1974) is only four months away. It therefore seems appropriate to officially modify the specification to account for the suggested modifications, and to declare a moratorium on the incorporation of additional suggestions until after the switchover. (Of course, no moratorium on the specification of additional options is required.) The two attached documents represent the revised TELNET Protocol specifications; they replace NIC #15372, TELNET Protocol Specification, and NIC #15373, TELNET Option Specifications. The remainder of this RFC summarizes the changes. Page numbers refer to the earlier documents. Changes to TELNET Protocol Specification Page 8 - The phrase "blocked on input" is removed (see RFC #513). Page 9, 10 - An additional use of IP is mentioned (see RFC #529). Page 10 - The explanation of AO is expanded (see RFC #513). Page 11 - The definition of "'print position' (e.g., an overstrike)" is clarified (see RFC #513). Page 11, 12 - The description of the TELNET Synch Signal is reworked to be in conformance with the ideas of RFC #529 (also see RFC #513). Page 14 - The explanation of the CR-NUL convention is expanded (see RFC #513). Page 16 - An additional command, End of Subnegotiation Parameters (SE) is defined (see RFCs 513, 529). Changes to TELNET Option Specifications Pages 2, 3 - Use of the command SE is explained (see RFCs 513, 529). Page 3 - Doubling of IAC in subnegotiation parameters is required (see RFC #513). [This RFC was put into machine readable form for entry] [into the online RFC archives by Helene Morin, Via Genie 12/99]
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§1Why the Documents Were Revised
Almost four months had passed since publication of the new Telnet Protocol specification, and the planned switch from old Telnet to new Telnet was four months away. RFC 562 says it was time to incorporate the suggestions already made.
The attached revised protocol and option documents replace the earlier NIC documents.
The new Telnet documents had received a small number of suggested changes, and a transition date was getting close. The author proposes incorporating the changes and then holding the specification steady.
§2Protocol Clarifications
The RFC lists changes by page of the earlier protocol document. These include removing the phrase blocked on input, expanding explanations of IP and AO, clarifying print position, revising the SYNCH description to align with RFC 529, and expanding the CR-NUL explanation.
It also defines the End of Subnegotiation Parameters command, SE.
Several changes explain existing Telnet behavior more clearly. Another adds a command to mark the end of option subnegotiation parameters.
§3Option Rules and the Moratorium
The revised option specifications explain the use of SE and require that an IAC byte inside subnegotiation parameters be doubled.
RFC 562 declares a moratorium on incorporating additional suggestions until after the switchover. It explicitly says the moratorium does not prevent specifying additional options.
The option rules define how to end parameter data and how to represent an IAC byte within it. Other specification changes pause during the transition, but new options remain possible.