Telnet Data Entry Terminal option(9)

　　6. Sample Interaction

　　The nomenclature of RFC726will be used to describe this example. To　quote that RFC:

　　"S:" is sent from serving host to using host.

　　"U:" is sent from using host to serving host.

　　"T:" is entered by the terminal user.

　　"P:" is printed on the terminal.

　　Text surrounded by square brackets([]) is commentary. Text　surrounded by angle brackets (<>) is to be taken as a single unit.

　　E.g, carriage return is , and the decimal value 27 is　represented <27>.

　　We assume that the user has established the Telnet connection,　logged on, and an application program has just been started either　by the user directly or through a canned start up procedure. The　presentation on the page is meant to merely group entities together　and does not imply the position of message boundaries. One should　assume that any part of the dialogue may be sent as one or many　messages. The first action of the program or Telnet is to negotiate　the DET option:

　　S:

　　U:

　　S:

[First negotiate the screen　size. In this case we are　asking the user the size of　the terminal. This could　have been done before the　DET option was negotiated.]

　　U:

　　U:<25>

　　S:<0>

　　S:

　　John Day [page 21]

　　NWG/RFC# 732 DAY 13-Sep-77 18:38 41762

　　Data Entry Terminal Option

　　U:<80> [Defines the screen to be

　　25 lines by 80 characters.

　　The server may use this　information when formatting　the screen.]

　　S:<0>

　　S:

　　Intensity> [Now set the terminal　attributes.]

　　U:

　　Levels Intensity>

　　S: [Erase the screen and start　sending the form.]

　　<0>

　　<5>Name:

　　<0><1>

　　<0>

　　<8>Address:

　　<0><4>

　　<0>

　　<17>Telephone number:

　　<32><4>

　　<0>

　　<24>Social Security Number:

　　<0><11> [Establish a field that　doesn't display what is　typed into it.]

　　<32><5>

　　<0> [Get permission to use　Blinking Attribute.]

　　U:

　　3 Levels Intensity>

　　S:

Intensity=1>　　Intensity=1><0><29>

　　Your SSN will not be printed.

　　The previous exchange has placed a form on the screen that looks like:

　　Name:

　　Address:

　　Telephone Number: Social Security Number:

　　"Your SSN will not be printed."　where the quoted string is blinking.

　　The terminal user is now free to fill in the form provided. He　positions the cursor at the beginning of the first field (this usually　is done by hitting the tab key) and begins typing. We do not show this　interaction since it does not generate any interaction with the User　Telnet program or the network. After the terminal user has completed　filling in the form, he strikes the transmit key to send the　unprotected part of the form, but first the User Telnet program　negotiates the Byte Macro Option to condense the Field Separator　subcommand:

　　U: [Negotiate Byte Macro　Option.]

　　S: [Define decimal 166 to be　the Field Separator　subcommand (see Appendix　3)]

　　U:

　　<166><6>

　　SEPARATOR IAC SE>

　　S:<166> [The server accepts the　macro.]

　　U:<0><6>

　　John Doe <166> 1515 Elm St., Urbana, Il 61801

　　<166>217-333-9999 <166> 123-45-6789 <166>

　　S:

　　Thank you.

　　And so on.

　　Appendix 1 - Subcommands, opcodes and syntax

　　1 EDIT FACILITIES

　　2 ERASE FACILITIES

　　3 TRANSMIT FACILITIES

　　4 FORMAT FACILITIES

　　5 MOVE CURSOR

　　6 SKIP TO LINE

　　7 SKIP TO CHAR

　　8 UP

　　9 DOWN

　　10 LEFT

　　11 RIGHT

　　12 HOME

　　13 LINE INSERT

　　14 LINE DELETE

　　15 CHAR INSERT

　　16 CHAR DELETE

　　17 READ CURSOR

　　18 CURSOR POSITION

　　19 REVERSE TAB

　　20 TRANSMIT SCREEN

　　21 TRANSMIT UNPROTECTED

　　22 TRANSMIT LINE

　　23 TRANSMIT FIELD

　　24 TRANSMIT REST OF SCREEN

　　25 TRANSMIT REST OF LINE

　　26 TRANSMIT REST OF FIELD

　　27 TRANSMIT MODIFIED

　　28 DATA TRANSMIT

　　29 ERASE SCREEN

　　30 ERASE LINE

　　31 ERASE FIELD

　　32 ERASE REST OF SCREEN

　　33 ERASE REST OF LINE

　　34 ERASE REST OF FIELD

　　35 ERASE UNPROTECTED

　　36 FORMAT DATA

　　37 REPEAT

　　38 SUPPRESS PROTECTION

　　39 FIELD SEPARATOR

　　40 FN