Contents / Chapter 7 / Appendix B /

APPENDIX A ESCAPE SEQUENCES

A.I Control Characters

The VT220 terminal has two character sets (C0 and C1) active at any one time, with C0 mapped to the lower 128 bytes in the 256 byte active character table and C1 mapped to the upper 128 bytes. There are also four graphic character sets (G0, G1, G2, and G3) that are stored internally and subsequently loaded with Designate Hard Character Set (DHCS) commands.

A.I.1 C0 Control Characters (00h to 1Fh)

Other C0 control characters are ignored.
See "Character Table" figure.

A.I.2 C1 Control Characters (80h to 9Fh)

C1 control character processing may be disabled by Ignore8BCtrl=Yes Option.

Other C1 control characters are ignored.
See "Character Table" figure.

A.II VT52 Escape Sequences

Supported

Unsupported

A.III ANSI / VT100 / VT220 Escape Sequences

ANSI sequences normally begins by the ANSI standard CSI sequence.

A.III.1 Terminal Selection (DECSCL)

CSI is "ESC [" ("1Bh 5Bh") OR "9Bh".

A.III.2 Character Set Selection (SCS)

A.III.2.1 Designating

Each VTXXX character set are coded between 20h / 7Fh. And cant be set by different ways in GL "Graphics Left" (00h to 7Fh) or GR "Graphics Right" (80h to FFh). See "Character Table" and "Setting And Designating"

• VT52 : Only "B" or "0" sets in GL (VT52 is a 7 Bits terminal) (No G0-G3 sets).
• VT100 : "B", "0" and "<" sets, selected in G0 to G3, and designated to GL (VT100 is a 7 Bits terminal).
• VT220 : "B", "0" and "<" sets, selected in G0 to G3, and designated to GL or GR (VT220 is a 8 Bits terminal)

WT Emulates the three character sets with a single 00h to FFh "PC" Font.
The character set supported by Wireless Telnet with VTX.FNT font are :

Downloading and designation of "soft character sets" is unsupported by WT.

Using SCS sequences, character sets are located in G0, G1, G2, G3. This makes the graphic sets available to map them into GL or GR using locking shifts (LS0L, LS1L, LS2L, LS3L, LS1R, LS2R and LS3R) or temporary shifts (SS2 and SS3).

Setting other fonts (437.fnt, 850.fnt, 852.fnt ...) with the [DisplayFont] section, and disabling the C1 control codes by Ignore8BCtrl=Yes WT Option allows a "PC-Like" display.

See also "Setting And Designating" figure.

A.III.2.2 Invoking

Characters in G0 to G3 may be invoked to GL or GR by the "Locking Shift" functions.

Characters in G2 and G3 may be invoked into GL by the "Single Shift" functions. Single shift applies only to the next character, then returns to the normal Graphic set.

See also "Setting And Designating" figure.

A.III.3 Select C1 Controls

See WT Bits8Mode= Option.

DEC Documentation says ...
<<"Digital recommends that you use DECSCL sequences instead of Select C1 Controls because DECSCL performs a soft reset putting the terminal in a "known" state in addition to setting the terminal mode and C1 control state">>.

A.III.4 Terminal Mode

CSI is "ESC [" ("1Bh 5Bh") OR 9Bh.

Unsupported

A.III.5 Cursor Positioning

Pn, Pl, Pc are variable numeric parameters. If you select no parameter WTnCE assumes the parameter equals 1.

CSI is "ESC (" 5"1Bh 5Bh") OR 9Bh.

A.III.6 Character Attributes (SGR)

The Select Character Attributes (DECSCA) sequences are unsupported.
The Line Attribute sequences (DECDHL, DECSHL, DECSWL and DECDWL) are unsupported.
CSI is "ESC [" ("1Bh 5Bh") OR 9Bh.

A.III.7 Insertion / Deletion

Pn is a variable numeric parameter. If you select no parameter WT assumes the parameter equals 1.

CSI is "ESC [" ("1Bh 5Bh") OR 9Bh.

A.III.8 Erasing Characters

Pn is a variable numeric parameter. If you select no parameter WT assumes the parameter equals 0.

CSI is "ESC [" ("1Bh 5Bh") OR 9Bh.

A.III.9 Set Scroll Area

A.III.10 Printing

Auto Print Mode, Print Cursor Line and Print Screen are unsupported.
CSI is "ESC [" ("1Bh 5Bh") OR 9Bh.

A.III.11 Terminal Reports

A.III.12 Terminal Reset

A.III.13 Tabulations

A.IV Supplemental ANSI Escape Sequences

Pn is a variable numeric parameter. If you select no parameter WT assumes the parameter equals 1.

A.V ROI Escape Sequences

These sequences are supported if RoiEscSeq=Yes

A.VI TELXON Escape Sequences

These sequences are supported if TelxonEscSeq=Yes
Telxon escape sequences are in the following format : ESC R nn pp ESC \.
Where nn is a two-digit command number, and pp a two-digit command parameter.

A.VII Sent Escape Sequences

Keyboard keys send characters defined by terminal keyboard layout and standard translation process. (Normal translation is to send the character represented by lower weight byte of scan code). You can see scan codes and translations in the terminal through the Display Configuration screen.

All scan codes between 0100h - to FF00h are "Function Keys Scan Codes" and are always trapped by application. If the Function Scan Code is not found in any translation routine, the key is ignored (has no action). If the Scan Code is found in any translation routine, the corresponding string is sent to the host. Strings are always supplied into their "7 Bits format", and translation may be done if the terminal is operating in "8 Bits Mode".

A.VII.1 Translation Routines

Translation routines are "user-defined" translation strings associated with an Scan Code. The following routines are defined:

* User-Defined. Following [VT_SCANCODES] section in WTnCeVT configuration file. Supplies a string associated with a scan code (Normal 0000h-00FFh or Function 0100h-FFFFh).
You can see the active translations in the terminal: tap the configure button in the main screen and then tap Keyboard Test.

* Normal Function Keys (Pressing [FUNC] then [n] key, with n=numeric key).  The active translation keys depends of the terminal type choose by user or negotiated with Telnet server. The corresponding [FNKEYS_<name>] section in the WTnCeVT configuration file is copied into (terminal type can be dynamically changed during connection).
You can see the active translations in the terminal by the Keyboard Test screen.

* Shifted Function Keys (Pressing [SHIFT] then [FUNC] then [n] key, with n=numeric key).  The active translation keys depends of the terminal type choose by user or negotiated with server. The corresponding [SFNKEYS_<name>] section in the WT configuration file is copied into (terminal type can be dynamically changed during connection).
You can see the active translations in the terminal by the Keyboard Test screen.

* Cursor Keys (Pressing Up, Down, Left or Right Arrow keys). The active translation keys depends of the terminal type choose by user or negotiated with server. The corresponding [CURKEYS_<name>] or [CURKEYSAP_<name>] section in the WTnCeVT configuration file is copied into (terminal type can be dynamically changed during connection).
Switching between "Normal" and "Application" cursor keys can be dynamically done in some terminal types by escape sequences (See Cursor Keys in Terminal Modes) .
Modify the WTnCeVT CurKeysApp= Option to set by default "Normal" or "Application" cursor keys.
You can see the active translations in the terminal with the Keyboard Test screen.

The WTnCeVT Configuration file contains the "standard" sequences following each terminal type emulation. Those standards can be modified by user to allow application-specific keys (see Chapter 5).

A.VII.2 7 and 8 Bits Mode

7 Bits and 8 Bits operating mode may modify the strings sent by the Terminal to the Host. 

• In "7 Bits Mode" the strings are sent "as is". 
• In "8 Bits Mode" strings that start with CSI or SS3 are translated from the 7 Bits format (2 characters) to their 8 Bits Format (single character). 

7 Bits or 8 Bits operating mode may be choose by several ways :

• By WT "Bits8Mode=" Option. 
          Bits8Mode=No, operates in 7 Bits mode (No translation)
          Bits8Mode=Yes, operates in 8 Bits mode (Translation)
• By "Terminal Selection (DECSCL)", dynamically.
• By "Select C1 Controls", dynamically.

8 Bits Mode is automatically turned off if VT52 or VT100 terminal types are selected (those are 7 Bits only terminals).
8 Bits Mode have sense only in VT220 or ANSI WT terminal emulation modes.

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