    TELNET OUTPUT VERTICAL TABSTOPS OPTION
    RFC 656, NIC 31159 (Oct. 25, 1974)"
    D. Crocker (UCLA-NMC)
    Online file: [ISI]<DCROCKER>NAOVTS.TXT

                    TELNET OUTPUT VERTICAL TABSTOPS OPTION

    1. Command name and code
       NAOVTS 14
          (Negotiate About Vertcial Tabstops)

    2. Command meanings
       In the following, we are discussing a simplex connection, as described in
       the NAOL and NAOP Telnet Options specifications.
          IAC DO NAOVTS
             The data sender requests or agrees to negotiate about output
             vertical tabstops with the data receiver.  In the case where
             agreement has been reached and in the absence of further
             subnegotiations, the data receiver is assumed to be handling output
             vertical tabstop considerations.
          IAC DON'T NAOVTS
             The data sender refuses to negotiate about output vertical tabstops
             with the data receiver, or demands a return to the unnegotiated
             default mode.
          IAC WILL NAOVTS
             The data receiver requests or agrees to negotiate about output
             vertical tabstops with the sender.  In the case where agreement has
             been reached and in the absence of further subnegotiations, the data
             receiver alone is assumed to be handling output vertical tabstop
             considerations.
          IAC WON'T NAOVTS
             The data receiver refuses to negotiate about output vertical
             tabstops, or demands a return to the unnegotiated default mode.
          IAC SB NAOVTS DS <8-bit value> ... <8-bit value> IAC SE
             The data sender specifies, with the 8-bit value(s), which party
             should handle output vertical tabstop considerations and what the
             stops should be.  The code for DS is 1.
          IAC SB NAOVTS DR <8-bit value> ... <8-bit value> IAC SE
             The data receiver specifies, with the 8-bit value(s), which party
             should handle output vertical tabstop considerations and what the
             stops should be.  The code for DR is 0.

    3. Default
       DON'T NAOVTS/WON'T NAOVTS.
          In the default absence of negotiations concerning which party, data
          sender or data receiver, is handling output vertical tabstop
          considerations, neither party is required to handle vertical tabstops
          and neither party is prohibited from handling them; but it is
          appropriate if at least the data receiver handles vertical tabstop
          considerations, albeit primitively.

    4. Motivation for the Option
       Please refer to section 4 of the NAOL and of the NAOVTS Telnet option
       descriptions.

    5. Description of the Option
       The data sender and the data receiver use the 8-bit value(s) along with
       the DS and DR SB commands as follows (multiple 8-bit values are allowed
       only if each is greater than zero and less than 251):

          8-bit value                      Meaning

          0            Command sender suggests that he alone will handle
                       the vertical tabstops, for the connection.
          1 to 250     Command sender suggests that the other party alone
                       should handle the stops, but suggests that the
                       indicated value(s) be used.  Each value is the line
                       number, relative to the top of the printer page or
                       terminal screen, that is to be set as a vertical
                       tabstop.
          251 to 254   Not allowed, in order to be compatible with
                       related Telnet options.
          255          Command sender suggests that the other party alone
                       should handle output vertical tabstops and
                       suggests nothing about how it should be done.

       The guiding rules are that:

          1) if neither data receiver nor data sender wants to handle output
          vertical tabstops, the data receiver must do it, and
          2) if both data receiver and data sender want to handle output vertical
          tabstops, the data sender gets to do it.

    The reasoning for the former rule is that if neither wants to do it, then
    the default in the NAOVTS option dominates.  If both want to do it, the
    sender, who is presumed to have special knowledge about the data, should be
    allowed to do it, taking into account any suggestions the receiver may make.
    This is necessary due to the assynchrony of network transmissions.
    As with all option negotiations, neither party should suggest a state
    already in effect except to refuse to negotiate; changes should be
    acknowledged; and once refused, an option should not be resuggested until
    "something changes" (e.g., another process starts).
    At any time, either party can disable further negotiation by giving the
    appropriate WON'T NAOVTS or DON'T NAOVTS command.