Telnet output formfeed disposition option (original) (raw)

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HISTORIC

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