the same horizontal position.

      All remaining codes do not cause the NVT printer to take any
      action.

      The sequence "CR LF", as defined, will cause the NVT to be
      positioned at the left margin of the next print line (as would,
      for example, the sequence "LF CR").  However, many systems and
      terminals do not treat CR and LF independently, and will have to
      go to some effort to simulate their effect.  (For example, some
      terminals do not have a CR independent of the LF, but on such
      terminals it may be possible to simulate a CR by backspacing.)
      Therefore, the sequence "CR LF" must be treated as a single "new
      line" character and used whenever their combined action is
      intended; the sequence "CR NUL" must be used where a carriage
      return alone is actually desired; and the CR character must be
      avoided in other contexts.  This rule gives assurance to systems
      which must decide whether to perform a "new line" function or a
      multiple-backspace that the TELNET stream contains a character
      following a CR that will allow a rational decision.

         Note that "CR LF" or "CR NUL" is required in both directions



 


RFC 854                                                         May 1983


         (in the default ASCII mode), to preserve the symmetry of the
         NVT model.  Even though it may be known in some situations
         (e.g., with remote echo and suppress go ahead options in
         effect) that characters are not being sent to an actual
         printer, nonetheless, for the sake of consistency, the protocol
         requires that a NUL be inserted following a CR not followed by
         a LF in the data stream.  The converse of this is that a NUL
         received in the data stream after a CR (in the absence of
         options negotiations which explicitly specify otherwise) should
         be stripped out prior to applying the NVT to local character
         set mapping.

      The NVT keyboard has keys, or key combinations, or key sequences,
      for generating all 128 USASCII codes.  Note that although many
      have no effect on the NVT printer, the NVT keyboard is capable of
      generating them.

      In addition to these codes, the NVT keyboard shall be capable of
      generating the following additional codes which, except as noted,
      have defined, but not reguired, meanings.  The actual code
      assignments for these "characters" are in the TELNET Command
      section, because they are viewed as being, in some sense, generic
      and should be available even when the data stream is interpreted
      as being some other character set.

      Synch

         This key allows the user to clear his data path to the other
         party.  The activation of this key causes a DM (see command
         section) to be sent in the data stream and a TCP Urgent
         notification is associated with it.  The pair DM-Urgent is to
         have required meaning as defined previously.

      Break (BRK)

         This code is provided because it is a signal outside the
         USASCII set which is currently given local meaning within many
         systems.  It is intended to indicate that the Break Key or the
         Attention Key was hit.  Note, however, that this is intended to
         provide a 129th code for systems which require it, not as a
         synonym for the IP standard representation.

      Interrupt Process (IP)

         Suspend, interrupt, abort or terminate the process to which the
         NVT is connected.  Also, part of the out-of-band signal for
         other protocols which use TELNET.




 


RFC 854                                                         May 1983


      Abort Output (AO)

         Allow the current process to (appear to) run to completion, but
         do not send its output to the user.  Also, send a Synch to the
         user.

      Are You There (AYT)

         Send back to the NVT some visible (i.e., printable) evidence
         that the AYT was received.

      Erase Character (EC)