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
