RFC 139 (rfc139) - Page 2 of 11
Discussion of Telnet Protocol
Alternative Format: Original Text Document
RFC 139 Discussion of TELNET Protocol 7 May 1971
Since it is not known how the current or future sites will specify
the mapping between the network-wide standard code (7 bit ASCII in an
8 bit field) and the codes expected from their own terminals, it
seems necessary to permit the user to cause every one of the 128
ASCII codes, plus (for full user power) selected control signals
(either of a TELNET control nature, or of a special terminal nature
such as break or attention).
There was strong feeling about the importance of the user/system
interface at the using site, but equally strong feeling that this
problem is one of local implementation and should reflect the using
site installation philosophy rather than the subject to network-wide
standards. Some topics of consideration in this area are:
1. How to represent special graphics, not available at the using
site, at the user's terminal.
2. Treatment of upper/lower case problem on TTY 33 and 35.
a. Representing lower-case output.
b. Providing users with shift and shift lock signals.
3. Incorporating editing capability in TELNET.
4. Extending user options in Network mode not available to local
users,
e.g., hold output
kill print
5. Permit users to specify how keyboard input is to be translated,
e.g., let a character from the terminal cause a specified
string to be sent by the user's TELNET.
In early discussions, there was pressure to get a simple statement of
protocol out early to permit early use of selected systems. The
counter pressure to provide a richer set of protocol in the first
release was also present. Work started in the direction of the
latter, but the complexities introduced were not necessary for early
use of the network. The proposed solution to the TELNET protocol
problem seems to provide a mechanism for a minimum implementation (to
be discussed later) while providing a basis for developing richer
sets of protocol for present and future use in terminal applications,
process-process communications, and use by other conventions to pass
data or control information.
O'Sullivan