Telnet end of record option
Author(s): J. Postel
This RFC specifies a standard for the ARPA Internet community. It specifies a method for marking the end of records in data transmitted on Telnet...
Network Working Group J. Postel Request for Comments: 885 ISI December 1983 TELNET END OF RECORD OPTION This RFC specifies a standard for the ARPA Internet community. Hosts on the ARPA Internet that need to mark record boundaries within Telnet protocol data are expected to adopt and implement this standard. 1. Command Name and Code END-OF-RECORD 25 2. Command Meanings IAC WILL END-OF-RECORD The sender of this command requests permission to begin transmission of the Telnet END-OF-RECORD (EOR) code when transmitting data characters, or the sender of this command confirms it will now begin transmission of EORs with transmitted data characters. IAC WON'T END-OF-RECORD The sender of this command demands to stop transmitting, or to refuses to begin transmitting, the EOR code when transmitting data characters. IAC DO END-OF-RECORD The sender of this command requests that the sender of data start transmitting the EOR code when transmitting data, or the sender of this command confirms that the sender of data is expected to transmit EORs. IAC DON'T END-OF-RECORD The sender of this command demands that the receiver of the command stop or not start transmitting EORs when transmitting data. 3. Default WON'T END-OF-RECORD DON'T END-OF-RECORD END-OF-RECORD is not transmitted. Postel [Page 1] RFC 885 December 1983 4. Motivation for the Option Many interactive systems use one (or more) of the normal data characters to indicate the end of an effective unit of data (i.e., a record), for example, carriage-return (or line-feed, or escape). Some systems, however, have some special means of indicating the end of an effective data unit, for example, a special key. This Telnet option provides a means of communicating the end of data unit in a standard way. 5. Description of the Option When the END-OF-RECORD option is in effect on the connection between a sender of data and the receiver of the data, the sender transmits EORs. It seems probable that the parties to the Telnet connection will transmit EORs in both directions of the Telnet connection if EORs are used at all; however, the use of EORs must be negotiated independently for each direction. When the END-OF-RECORD option is not in effect, the IAC EOR command should be treated as a NOP if received, although IAC EOR should not normally be sent in this mode. 6. Implementation Considerations As the EOR code indicates the end of an effective data unit, Telnet should attempt to send the data up to and including the EOR code together to promote communication efficiency. The end of record is indicated by the IAC EOR 2-octet sequence. The code for EOR is 239 (decimal). Postel [Page 2]