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Network Working Group Marvin Solomon Request for Comments: 884 Edward Wimmers

                                     University of Wisconsin - Madison
                                                         December 1983

                    TELNET TERMINAL TYPE OPTION

This RFC specifies a standard for the ARPA Internet community. Hosts on the ARPA Internet that exchange terminal type information within the Telnet protocol are expected to adopt and implement this standard.

1. Command Name and Code

 TERMINAL-TYPE    24

2. Command Meanings

 IAC WILL TERMINAL-TYPE

    Sender is willing to send terminal type information in a
    subsequent sub-negotiation

 IAC DO TERMINAL-TYPE

    Sender is willing to receive terminal type information in a
    subsequent sub-negotiation

 IAC DON'T TERMINAL-TYPE

    Sender refuses to accept terminal type information

 IAC WON'T TERMINAL-TYPE

    Sender refuses to send terminal type information

 IAC SB TERMINAL-TYPE SEND IAC SE

    Sender requests receiver to transmit his (the receiver's) terminal
    type. The code for SEND is 1. (See below.)

 IAC SB TERMINAL-TYPE IS ... IAC SE

    Sender is stating the name of his terminal type. The code for IS
    is 0. (See below.)

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3. Default

 DON'T TERMINAL-TYPE

 WON'T TERMINAL-TYPE

 Terminal type information will not be exchanged.

4. Motivation for the Option

 This option allows a telnet server to determine the type of terminal
 connected to a user telnet program.  The transmission of such
 information does not immediately imply any change of processing.
 However, the information may be passed to a process, which may alter
 the data it sends to suit the particular characteristics of the
 terminal. For example, some operating systems have a terminal driver
 that accepts a code indicating the type of terminal being driven.
 Using the TERMINAL TYPE and BINARY options, a telnet server program
 on such a system could arrange to have terminals driven as if they
 were directly connected, including such special functions as cursor
 addressing, multiple colors, etc., not included in the Network
 Virtual Terminal specification.  This option fits into the normal
 structure of TELNET options by deferring the actual transfer of
 status information to the SB command.

5. Description of the Option

 WILL and DO are used only to obtain and grant permission for future
 discussion. The actual exchange of status information occurs within
 option subcommands (IAC SB TERMINAL-TYPE...).

 Once the two hosts have exchanged a WILL and a DO, the sender of the
 WILL TERMINAL-TYPE is free to transmit type information, spontan-
 eously or in response to a request from the sender of the DO.  At
 worst, this may lead to transmitting the information twice. Only the
 sender of the DO may send requests (IAC SB TERMINAL-TYPE SEND IAC SE)
 and only the sender of the WILL may transmit actual type information
 (within an IAC SB TERMINAL-TYPE IS ... IAC SE command).

 The terminal type information is an NVT ASCII string.  Within this
 string, upper and lower case are considered equivalent.  A few
 terminal type names useful in the context of IBM systems are listed
 below.  It is anticipated that additional names will be added in the
 future.  The complete list of valid terminal types will be found in
 the latest "Assigned Numbers" RFC.

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RFC 884 December 1983

 The following is an example of use of the option:

    Host1: IAC DO TERMINAL-TYPE

    Host2: IAC WILL TERMINAL-TYPE

       (Host2 is now free to send status information at any time.
       Solicitations from Host1 are NOT necessary. This should not
       produce any dangerous race conditions. At worst, two IS's will
       be sent.)

    Host1 (perhaps): IAC SB TERMINAL-TYPE SEND IAC SE

    Host2:

       IAC SB TERMINAL-TYPE IS IBM-3278-2 IAC SE

6. Implementation Suggestions

 The "terminal type" information may be any NVT ASCII string meaning-
 ful to both ends of the negotiation.  The list of suggestions below
 is intended to minimize confusion caused by alternative "spellings"
 of the terminal type.  For example, confusion would arise if one
 party were to call a terminal "IBM3278-2" while the other called it
 "IBM-3278/2".  There is no negative acknowledgement for a terminal
 type that is not understood, but certain other options (such as
 switching to BINARY mode) may be refused if a valid terminal type
 name has not been specified.  In some cases, a particular terminal
 may be known by more than one name, for example a specific type and a
 more generic type.  In such cases, the sender of the TERMINAL-TYPE IS
 command should reply to successive TERMINAL-TYPE SEND commands with
 the various names, from most to least specific.  In this way, a
 telnet server that does not understand the first response can prompt
 for alternatives.  However, it should cease sending TERMINAL-TYPE
 SEND commands after receiving the same response two consecutive
 times.  Similarly, a sender should indicate it has sent all available
 names by repeating the last one sent.

 Here are a few terminal types useful in the IBM environment:

    IBM-3275-2
    IBM-3276-2
    IBM-3276-3
    IBM-3276-4
    IBM-3277-2
    IBM-3278-2
    IBM-3278-3
    IBM-3278-4

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RFC 884 December 1983

    IBM-3278-5
    IBM-3279-2
    IBM-3279-3

 Here are a few terminal types useful in the TOPS20 environment:

    ANN-ARBOR-AMBASSADOR
    CONCEPT-100
    DATAMEDIA-2500
    DEC-LA30
    DEC-VT100
    DEC-VT52
    EXECUPORT-4000
    HAZELTINE-1500
    HP-2621
    HP-2640
    HP-2645A
    HP-2649
    NETWORK-VIRTUAL-TERMINAL
    TEKTRONIX-4025
    TELERAY-1061
    TELETYPE-33
    TELETYPE-37
    TELEVIDEO-950
    TERMINET-300
    TI-700
    ZENITH-H19

 Here are a few terminal types used in the Unix environment:

    ADDS-CONSUL-980
    ADDS-REGENT-200
    ANDERSON-JACOBSON-832
    ANN-ARBOR-AMBASSADOR
    BITGRAPH
    CDI-1203
    COMPUCOLOR-II
    CONCEPT-100
    DATA-GENERAL-6053
    DATAGRAPHIX-132A
    DATAMEDIA-3045A
    DATAPOINT-3360
    DEC-DECWRITER-II
    DEC-GT40
    DEC-VT52
    DELTA-DATA-5000
    DIABLO-1620
    EXECUPORT-4000

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RFC 884 December 1983

    GENERAL-TERMINAL-100A
    HAZELTINE-1500
    HAZELTINE-2000
    HP-2621
    HP-2640A
    HP-2645
    HP-2649A
    IBM-3101
    INFOTON-100
    LSI-ADM-3
    MICROTERM-ACT-V
    MICROTERM-MIME-2
    NETWORK-VIRTUAL-TERMINAL
    PERKIN-ELMER-1100
    PLASMA-PANEL
    SUPERBEE-III-M
    TEKTRONIX-4014
    TELERAY-3700
    TELETYPE-33
    TELETYPE-37
    TELEVIDEO-912
    TERMINET-300
    TI-700
    TI-733
    TI-745
    VISUAL-200
    XEROX-1720
    ZENITH-H19
    ZENTEC-30

 The type "UNKNOWN" should be used if the type of the terminal is
 unknown or unlikely to be recognized by the other party.

 The complete and up-to-date list will be maintained in the "Assigned
 Numbers".

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