Telnet output horizontal tabstops option (original) (raw)

[RFC Home] [TEXT|PDF|HTML] [Tracker] [IPR] [Info page]

HISTORIC

TELNET OUTPUT HORIZONTAL TABSTOPS OPTION RFC 653, NIC 31156 (Oct. 25, 1974) D. Crocker (UCLA-NMC) Online file: [ISI]NAOHTS.TXT

           TELNET OUTPUT HORIZONTAL TABSTOPS OPTION

1. Command name and code NAOHTS 11 (Negotiate About Output Horizontal Tabstops)

2. Command meanings In the following, we are discussing a simplex connection, as described in the NAOL and NAOP Telnet options. IAC DO NAOHTS The data sender requests or agrees to negotiate about output horizontal 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 horizontal tabstops. IAC DON'T NAOHTS The data sender refuses to negotiate about output horizontal tabstops with the data receiver, or demands a return to the unnegotiated default mode. IAC WILL NAOHTS The data receiver requests or agrees to negotiate about output horizontal 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 horizontal tabstops. IAC WON'T NAOHTS The data receiver refuses to negotiate about output horizontal tabstops, or demands a return to the unnegotiated default mode. IAC SB NAOHTS DS <8-bit value> ... <8-bit value> IAC SE The data sender specifies, with the 8-bit value(s), which party should handle output horizontal tabstop considerations and what the stops should be. The code for DS is 1. IAC SB NAOHTS DR <8-bit value> ... <8-bit value> IAC SE The data receiver specifies, with the 8-bit value(s), which party should handle output horizontal tabstop considerations and what the stops should be. The code for DR is 0.

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

4. Motivation for the Option Please refer to section 4 of the NAOL and of the NAOP 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 subcommands 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
               tabstops, for the connection.
  1 to 250     Command sender suggests that the other party alone
               should handle tabstop considerations, but suggests
               that the indicated value(s) be used. The value(s)
               are the column numbers, relative to the physical
               left side of the printer page or terminal screen,
               that are to be set.
  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 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 horizontal tabstops, the data receiver must do it, and (2) if both data receiver and data sender want to handle output horizontal 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 NAOHTS 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. 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 NAOHTS or DON'T NAOHTS command.