Network Working Group                                           G. Marcy
Request for Comments: 1096                    Carnegie Mellon University
                                                              March 1989


                    Telnet X Display Location Option

Status of This Memo

   This RFC specifies a standard for the Internet community.  Hosts on
   the Internet that transmit the X display location within the Telnet
   protocol are expected to adopt and implement this standard.
   Distribution of this memo is unlimited.

   This standard is modelled on RFC 1079 [1], the telnet terminal speed
   option.  Much of the text of this document is copied from that RFC.

Motivation

   When a user is running the Telnet client under the X window system,
   it is useful for the remote Telnet to know the X display location of
   that client.  For example, the user might wish to start other X
   applications from the remote host using the same display location as
   the Telnet client.  The purpose of this option is to make this
   information available through telnet connections.

. Command Name and Code

      X-DISPLAY-LOCATION (XDISPLOC)

      Code = 35

. Command Meanings

      IAC WILL X-DISPLAY-LOCATION

         Sender is willing to send the X display location in a
         subsequent sub-negotiation.

      IAC WON'T X-DISPLAY-LOCATION

         Sender refuses to send the X display location.

      IAC DO X-DISPLAY-LOCATION

         Sender is willing to receive the X display location in a
         subsequent sub-negotiation.




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RFC 1096            Telnet X Display Location Option          March 1989


      IAC DON'T X-DISPLAY-LOCATION

         Sender refuses to accept the X display location.

      IAC SB X-DISPLAY-LOCATION SEND IAC SE

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

      IAC SB X-DISPLAY-LOCATION IS ... IAC SE

         Sender is stating his X display location.  The code for IS is
         0.  (See below.)

. Default

      WON'T X-DISPLAY-LOCATION

         The X display location will not be exchanged.

      DON'T X-DISPLAY-LOCATION

         The X display location will not be exchanged.

. 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 X-DISPLAY-LOCATION...).

   Once the two hosts have exchanged a WILL and a DO, the sender of the
   DO X-DISPLAY-LOCATION is free to request the X display location.
   Only the sender of the DO may send requests (IAC SB X-DISPLAY-
   LOCATION SEND IAC SE) and only the sender of the WILL may transmit
   actual X display location (within an IAC SB X-DISPLAY-LOCATION IS ...
   IAC SE command).  The X display location may not be sent
   spontaneously, but only in response to a request.

   The X display location is an NVT ASCII string.  This string follows
   the normal Unix convention used for the DISPLAY environment variable,
   e.g.,

         <host>:<dispnum>[.<screennum>]

   No extraneous characters such as spaces may be included.

      The following is an example of use of the option:




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RFC 1096            Telnet X Display Location Option          March 1989


         Host1: IAC DO X-DISPLAY-LOCATION

         Host2: IAC WILL X-DISPLAY-LOCATION

      (Host1 is now free to request status information at any time.)

         Host1: IAC SB X-DISPLAY-LOCATION SEND IAC SE

         Host2: IAC SB X-DISPLAY-LOCATION IS "SRI-NIC.ARPA:0.0" IAC SE

      (This command is 22 octets.)

. Implementation Suggestions

   Since the X display location may not contain a hostname on the client
   host, i.e., ":0" or "unix:0.0", the Telnet client will need to modify
   the location appropriately before sending it on to the remote Telnet.

Reference

   []  Hedrick, C., "Telnet Terminal Speed Option", RFC 1079,
        Rutgers University, December, 1988.

Author's Address:

   Glenn A. Marcy
   Carnegie Mellon University
   School of Computer Science
   Pittsburgh, PA 15213-3890

   Phone: (412) 268-7669

   Email: Glenn.Marcy@CS.CMU.EDU


















Marcy                                                           [Page 3]