Telnet Data Entry Terminal option(10)

　　41 ERROR

　　Appendix 2 - Error Codes

　　1 Facility not previously negotiated.

　　2 Illegal subcommand code.

　　3 Cursor Address Out of Bounds.

　　4 Undefined FN value.

　　5 Can't negotiate acceptable line width.

　　6 Can't negotiate acceptable page length.

　　7 Illegal parameter in subcommand.

　　8 Syntax error in parsing subcommand.

　　9 Too many parameters in subcommand.

　　10 Too few parameters in subcommand.

　　11 Undefined parameter value

　　12 Unsupported combination of Format Attributes

　　Appendix 3 - Use of the Byte Macro Option

　　One of the major drawbacks of the DET option is that because the　functions are encoded as Telnet option subnegotiations a fairly high　overhead is incurred. A function like Character Insert which is　encoded as a single byte in most terminals requires six bytes in the　DET option. Originally the only other solution that would have　accomplished the same transparency that the use of subcommands　provides would have been to define additional Telnet control　functions. However, since this would entail modification of the Telnet　protocol itself, it was felt that this was not a wise solution. Since　then the Telnet Byte Macro Option (RFC729) has been defined. This　option allows the user and server Telnets to map an arbitrary　character string into a single byte which is then transferred over the　net. Thus the Byte Macro Option provides the means for implementations　to avoid the overhead for heavily used subcommands. The rest of this　appendix suggests how the Byte Macro Option should be applied to the　DET option.

　　In keeping with the specification of the Byte Macro Option, macro　bytes will be chosen from the range 128 to 239. For the DET option, it　is suggested that macro bytes be chosen by adding the subcommand code　to 128. In addition, an unofficial DET subcommand might be defined　indicating that each side was willing to support macro bytes for all　subcommands (but not necessarily support all of the subcommands　themselves) according to this algorithm. This subcommand would be:

　　IAC SB DET DET-MACRO IAC SE subcommand code: 254　where may have the values of the Telnet option　negotiation:

　　251 WILL

　　252 WONT

　　253 DO

　　254 DONT

　　This subcommand is sent by a Telnet implementation to indicate its　willingness to adopt byte macros for all of the DET subcommands　according to the following algorithm:

　　The macro byte for subcommand i will be i+128 and will represent the　following string for parameterless subcommands:

　　IAC SB DET IAC SE

　　and the following string for subcommands with parameters:

　　IAC SB DET

　　The default setting for this subcommand is that the macros are not　in effect, in other words,

    IAC SB DET DET-MACRO WONT IAC SE

　　IAC SB DET DET-MACRO DONT IAC SE

　　Negotiation of this subcommand follows the same rules as　negotiations of the Telnet options.

　　References

　　1. ADM-1 Interactive Display Terminal Operator's Handbook　Lear-Siegler, Inc. 7410-31.

　　2. ADM-Interactive Display Terminal Operator's Handbook　Lear-Siegler, Inc. EID, 1974.

　　3. Burroughs TD 700/800 Reference Manual, Burroughs Corp., 1973

　　4. Burroughs TD 820 Reference Manual, Burroughs Corp. 1975.

　　5. CC-40 Communications Station: General Information Manual.

　　Computer Communication, Inc. Pub. No. MI-1100. 1974.

　　6. Crocker, David. "Telnet Byte Macro Option," RFC729, 1977.

　　7. Data Entry Virtual Terminal Protocol for Euronet, DRAFT, 1977.

　　8. Day, John. "A Minor Pitfall in the Telnet Protocol," RFC728,　1977.

　　9. Hazeltine 2000 Desk Top Display Operating Instructions. Hazeltine　IB-1866A, 1870.

　　10. How to Use the Consul 980: A Terminal Operator's Guide and　Interface Manual. Applied Digital Data Systems, Inc. 98-3000.

　　11. How to Use the Consul 520: A Terminal Operator's Guide and　Interface Manual. Applied Digital Data Systems, Inc. 52-3000.

　　12. Honeywell 7700 Series Visual Information Projection (VIP)

　　Systems: Preliminary Edition. 1973.

　　13. An Introduction to the IBM 3270 Information Display System. IBM GA27-2739-4. 1973.

　　14. Naffah, N. "Protocole Appareil Virtuel type Ecran" Reseau　Cyclades. TER 536. 1976.

　　15. Postel, Jon and Crocker, David. "Remote Controlled Transmission and Echoing Telnet Option", RFC726NIC 39237, Mar. 1977.

　　16. Schicker, Peter. "Virtual Terminal Protocol (Proposal 2). INWG Protocol Note #32., 1976.

　　17. UNISCOPE Display Terminal : Programmer Reference . Sperry- Univac　UP-7807 Rev. 2, 1975.

　　18. Universal Terminal System 400: System Description. Sperry- Univac　UP-8357, 1976.

　　19. Walden, David C. "Telnet Output Line Width Option." NIC # 20196,　1973, also in ARPANET Protocol Handbook, 1976.

　　20. Walden, David C. "Telnet Output Page Size" NIC # 20197, 1973,　also in ARPANET Protocol Handbook, 1976.