rfc655.txt

RFC 相关的技术文档

TELNET OUTPUT FORMFEED DISPOSITION OPTION
RFC 655, NIC 31158 (Oct. 25, 1974)
D. Crocker (UCLA-NMC)
Online file: [ISI]<DCROCKER>NAOFFD.TXT

              TELNET OUTPUT FORMFEED DISPOSITION OPTION

1. Command name and code
   NAOFFD - 13
      (Negotiate About Output Formfeed Disposition)

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

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

4. Motivation for the Option
   Please refer to section 4 of the NAOL and of the NAOFFD Telnet option 
   descriptions.

5. Description of the Option
   The data sender and the data receiver use the 8-bit value along with the
   DS and DR SB commands as follows:

      8-bit value                      Meaning                       

      0            Command sender suggests that he alone will handle  
                   formfeeds, for the connection.                     
      1 to 250     Command sender suggests that the other party alone 
                   should handle formfeeds, but suggests that 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.
      251          Command sender suggests that the other party alone 
                   handle formfeeds, but suggests that each           
                   occurrence of the character be replaced by         
                   carriage-return/line-feed.                         
      252          Command sender suggests that the other party alone 
                   handle formfeeds, but suggests that they be        
                   discarded.                                         
      253          Command sender suggests that the other party alone 
                   should handle formfeeds, but suggests that         
                   formfeeds be simulated.                            
      254          Command sender suggests that the other party alone 
                   should handle output formfeeds but suggests        
                   waiting for a character to be transmitted (on the  
                   other simplex connection) before sending more      
                   data. 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 formfeeds 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 
      formfeeds, the data receiver must do it, and
      2) if both data receiver and data sender want to handle output
      formfeeds, 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 NAOFFD 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 formfeed character by enough line-feeds (only)
   to advance the paper (or line-pointer) to the top of the next page
   (or to the top of the terminal screen).  Note that delays,
   controlled by the data sender, must consist of NUL characters
   inserted immediately after the formfeed character.  This is
   necessary due to the assynchrony of network transmission.  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 NAOFFD or DON'T NAOFFD command.