RFC653

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

           TELNET OUTPUT HORIZONTAL TABSTOPS OPTION

Command name and code

NAOHTS 11 (Negotiate About Output Horizontal Tabstops)

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.

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.

Motivation for the Option

Please refer to section 4 of the NAOL and of the NAOP Telnet option descriptions.

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.