Telnet Data Entry Terminal option(6)

　　Data sent to the terminal or the Using Host for unwritten areas of　the screen not in the scope of the count should be displayed with　the default values of the format map. The default values are No　Blinking, Normal Video, No Justification, No Protection and Normal　Intensity. For example, suppose a FORMAT DATA subcommand was sent to　the terminal with attributes Blinking and Protected and a　count of 5 followed by the string "Name: John Doe". The string　"Name:" would be protected and blinking, but the string "John Doe"　would not be.

　　This subcommand is used to format data to be displayed on the screen　of the terminal. The describes the attributes that the　field bytes wide should have. This field is to start at the　position of the cursor when the command is acted upon. The next　displayable characters in the data stream are used to fill　the field. Subsequent REPEAT subcommands may be used to specify the　contents of this field. If the sender specifies attributes that have　not been agreed upon by the use of the Format Facility subcommand,　the Telnet process should send an Error Subcommand to the sender,　　but format the screen as if the bit had not been set.

　　IAC SB DET REPEAT IAC SE subcommand code: 37

　　where is a positive 8-bit binary integer. is an 8-bit　byte containing an ASCII character.

　　This subcommand is used to perform data compression on data being　transferred to the terminal by encoding strings of identical　characters as the character and a count. The repeated characters may　be part of a field specified　IAC SB DET SUPPRESS PROTECTION IAC SE　subcommand code: 38

　　where may have the values of the Telnet option　negotiation:

　　251 WILL

　　252 WONT

　　253 DO

　　254 DONT

　　This subcommand is used to suppress the field protection in a　non-destructive manner. Many data entry terminals provide the means　by which protection may be turned on and off without modifying the　contents of the screen or the terminal's memory. Thus, the　protection may be turned off and back on without retransmitting the　form.

　　The default setting of the option is that protection is on, in other　words

　　IAC SB DET SUPPRESS PROTECTION WONT IAC SE

　　IAC SB DET SUPPRESS PROTECTION DONT IAC SE

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

　　IAC SB DET FIELD SEPARATOR IAC SE subcommand code: 39

　　It is necessary when transmitting only the unprotected portion of　the screen to provide a means for delimiting the fields. Existing　DET's use a variety of ASCII characters such as Tab, Group　Separator, Unit Separator, etc. In order to maintain transparency of　the NVDET this subcommand is used to separate the fields. Clearly,　this incurs rather high overhead. This overhead can be avoided by　using the Byte Macro Option (see Appendix 3).

　　Miscellaneous Commands

　　IAC SB DET FN IAC SE subcommand code: 40