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D. Crocker (UCLA-NMC) RFC 658, NIC 31161 (Oct. 25, 1974) Online file: [ISI]<DCROCKER>NAOLFD.TXT

                TELNET OUTPUT LINEFEED DISPOSITION

1. Command name and code

 NAOLFD 16 
    (Negotiate About Output Linefeed Disposition)

2. Command meanings

 In the following, we are discussing a simplex connection, as described in 
 the NAOL and NAOP Telnet Options.
    IAC DO NAOLFD 
       The data sender requests or agrees to negotiate about output
       linefeed disposition 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
       linefeed considerations.
    IAC DON'T NAOLFD 
       The data sender refuses to negotiate about output linefeed
       disposition with the data receiver, or demands a return to the
       unnegotiated default mode.
    IAC WILL NAOLFD 
       The data receiver requests or agrees to negotiate about output
       linefeed disposition 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 linefeed
       considerations.
    IAC WON'T NAOLFD 
       The data receiver refuses to negotiate about output linefeed 
       disposition, or demands a return to the unnegotiated default mode. 
    IAC SB NAOLFD DS <8-bit value> IAC SE
       The data sender specifies, with the 8-bit value, which party should 
       handle output linefeeds and what their disposition should be.  The 
       code for DS is 1.
  IAC SB NAOLFD DR <8-bit value> IAC SE
       The data receiver specifies, with the 8-bit value, which party
       should handle output linefeeds and what their disposition should
       be.  The code for DR is 0.

3. Default

 DON'T NAOLFD/WON'T NAOLFD.
    In the default absence of negotiations concerning which party, data
    under or data receiver, is handling output linefeed considerations,
    neither party is required nor prohibited from handling linefeeds; but
    it is appropriate if at least the data receiver handles them, albeit
    primitively.

4. Motivation for the Option

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

 5. Description of the Option

 The data sender and the data receiver use the 8-bit value along with DS
 and DR SB commands as follows:

    8-bit value         Meaning

    0            Command sender suggests that he alone will handle  
                 linefeeds, for the connection.                     
    1 to 250     Command sender suggests that the other party alone 
                 should handle linefeeds, but suggests that a delay 
                 of the indicated value be used.  The value is the   
                 number of character-times to wait or number of     
                 NULs to insert in the data stream before sending   
                 the next data character.  (See qualifications, below.)
    251          Not allowed, in order to be compatible with        
                 related Telnet options.                            
    252          Command sender suggests that the other party alone 
                 handle linefeeds, but suggests that they be discarded.
    253          Command sender suggests that the other party alone 
                 should handle linefeeds, but suggests that
                 linefeeds be simulated.                            
    254          Command sender suggests that the other party alone 
                 should handle output linefeeds but suggests        
                 waiting for a character to be transmitted (on the  
                 other simplex connection) before sending more      
                 data.  (See qualifications, below.) Note that, due  
                 to the assynchrony of the two simplex connections, 
                 phase problems can occur with this option.         
    255          Command sender suggests that the other party alone 
                 should handle output linefeeds 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 
    linefeeds, the data receiver must do it, and
    2) if both data receiver and data sender want to handle output linefeed 
    disposition, 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 NAOLFD 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.  Simulation is defined as the replacement of the linefeed character
 by new-line (see following) and enough blanks to move the print head (or
 line pointer) to the same lateral position it occupied just prior to
 receiving the linefeed.  To avoid infinite recursion, such simulation is
 allowed only for linefeed characters that are not immediately preceded by
 carriage-returns (that is, part of a Telnet new-line combination).  It is
 assumed that linefeed simulation will be necessary for printers that do
 not have a separate linefeed (like the IBM 2741); in this case,
 end-of-line character padding can be specified through NAOCRD.  Any
 padding (0 < <8-bit-value> < 251) of linefeed characters is to be done
 for ALL linefeed characters.

 NOTE: Delays, controlled by the data sender, must consist of NUL
 characters inserted immediately after the character.  This is necessary
 due to the assynchrony of network transmissions.  Additionally, due to
 the presence of the Telnet end-of-line convention, it may be necessary to
 add carriage-return padding or delay after the associated linefeed (see
 NAOCRD Telnet option).  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 NAOLFD or DON'T NAOLFD command.