RFC658 - Telnet output linefeed disposition

D. Crocker (UCLA-NMC)RFC658, NIC 31161 (Oct. 25, 1974)Online file: [ISI]<DCROCKER>NAOLFD.TXT                  TELNET OUTPUT LINEFEED DISPOSITION1. 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.