vnterm(1V)

NAME
vnterm - X-terminal with Vietnamese

SYNTAX
vnterm [-/+vnk] [-/+vns] [-vne <erase_ASCII_code>] [regular_xterm_options]

DESCRIPTION
Version 3.4 of vnterm is an adaptation of the X11R6.5.1 xterm 1X command. This manual page describes only those features specific to vnterm ; please consult the manual page for xterm 1X for the rest of the story.

Vnterm allows the X-environment user to type and display Vietnamese text. The keyboard input scheme follows the 7-bit VIQR (VIetnamese Quoted-Readable) standard, which is based on the prevalent Vietnamese networking convention of placing Vietnamese diacritical marks after the vowel, for example: "Vie^.t Nam".

With the appropriate font setting, vnterm can display both 7-bit and 8-bit Vietnamese text. The 7-bit text is assumed to follow the VIQR standard, and the 8-bit text is according to VISCII (VIetnamese Standard Code for Information Interchange), both published by the Viet-Std working group (Viet-Std@Haydn.Stanford.EDU).

On start-up, vnterm attempts to set the tty line to 8-bit mode, with canonical echoing of control characters turned off (because the Vietnamese characters "A(? A(~ A^~ Y? Y~ Y." are encoded in the C0 control-character area).

OPTIONS
	-/+vnk          turn on/off Vietnamese keyboard filter (default on)
	-/+vns          turn on/off Vietnamese screen output (default off)
	-vne ASCII_code explicitly specify erase character

The keyboard and screen options above can also be found and set in the "VT Options" menu of vnterm , which you may access by clicking the CTRL-middle-mouse-button combination. The corresponding X resources are:
    	vnterm*font:				vn-r14
    	vnterm*vnFilterKeyboard:    on
    	vnterm*vnFilterScreen:      off
    	vnterm*vnEraseCharacter:    127

If vnFilterKeyboard is turned off, no keyboard processing is done and characters are reported to the underlying application as they are typed. With vnFilterKeyboard turned on, Vietnamese composition takes place.

The erase character (which is needed to backspace over the Vietnamese letter being composed) is figured from the terminal settings at the time vnterm is invoked. In those cases where it is necessary to specify another erase character, vnEraseCharacter may be used. The argument to this option is the decimal ASCII code for the desired erase character. Use 8 for backspace, and 127 for delete.

The vnFilterScreen setting is provided as a convenience to the user who wants to read 7-bit Vietnamese without having first to convert it to 8-bit format. When turned on, vnFilterScreen causes the displayed characters to be interpreted with exactly the same rules as those applied to keyboard input. This option is provided with Soc.Culture.Vietnamese readers explicitly in mind.

KEYBOARD INSTRUCTIONS
Vnterm starts up in Vietnamese typing mode. There are two other modes, English and Literal, each of which is initiated as described below.

Vietnamese Mode:
Type "\V" or "\v" to start Vietnamese mode, where Viet-Net style input is supported, for example:
    	Ca' kho^ng a(n muo^'i ca' u+o+ng
    	Con ca~i cha me. tra(m ddu+o+`ng con hu+\.

To prevent composition, use "\". The example above shows "hu+." which tells Vnterm that the ending period is a period and not a Vietnamese dot-below (da^'u na(.ng).

The diacritics (da^'u) are:
    	MARK      	CHAR	EXAMPLE
    	breve     	 (  	a(n na(n
    	circumflex	 ^  	nha^n co^ng
    	horn      	 +  	tu+o+ng tu+
    	acute     	 '  	choa'ng va'ng
    	grave     	 `  	lu` khu`
    	hook above 	 ?  	ho?i tha(m
    	tilde      	 ~  	ky~ ca`ng
    	dot below  	 .  	Tra.ng Nguye^n
    	dd        	 dd 	dda ti`nh
    	DD        	 DD 	DDo^ng So+n

English Mode:
Type "\M" or "\m" to start English mode, where Viet-Net style input is supported, but must be explicitly announced with a "\", for example:
    	C\a' kh\o^ng \a(n mu\o^'i c\a' \u+\o+ng
    	Con c\a~i cha m\e. tr\a(m \dd\u+\o+`ng con h\u+\.

This mode is useful if you type mostly English and don't want the trouble of having to type "\" to escape composition all the time.

Literal Mode:
Typing "\L" or "\l" starts the Literal mode, in which almost all keys are passed literally.

RESTRICTIONS

o   If your shell is tcsh, you may find that it's unfriendly to 8-bit data; this means Vietnamese characters cannot be used. Use sh in the vnterm window instead.

o   In some cases vnterm may fail to set the terminal mode correctly for 8-bits. This will happen when your shell is "smart" and undoes the settings performed by vnterm on start-up. In this case issue the command:
        	% stty -istrip cs8 pass8
    to set the terminal line for 8-bits.

o   Remember that the screen output filter only works strictly with 7-bit Vietnamese that is conformant to the VIQR standard. With the Viet-Net style text alone, there are potential ambiguities which vnterm will not interpret correctly, e.g., in displaying the question "La`m chi?", where the question mark will be taken to be a hook-above (da^'u ho?i), and the word displayed as "ch<i?>" (Vietnamese "thread") rather than as "chi<?>" (Vietnamese "what"). Note that "chi\?" will be correctly interpreted.

Occasionally, magic sequences such as "\V", "\M", and "\L" may appear in non-VIQR-conformant text which will change the state of the screen filter causing it not to display Vietnamese properly afterwards. When this happens, simply turn the screen filter off and on again, by using the CTRL-middle-mouse-button menu of vnterm.

AUTHOR
4.4BSD porting and X11R6 updating by David O'Brien <obrien@cs.ucdavis.edu>

Adapted from X11R5's xterm by Tin Le <tin@saigon.com>

Adapted from X11R4's xterm by the TriChlor Group, TriChlor@haydn.Stanford.EDU.

Thanks to Tuan P. Do (tuan@compass-da.com) for illustrating the need for the vnEraseCharacter specifier.

SEE ALSO

vietterm(1V), vnelvis(1V)

STANDARDS
Viet-Std Standardization Specification (Viet-Std@Haydn.Stanford.EDU)

RFC 1456 Vietnamese Standardization Working Group, "Conventions for Encoding the Vietnamese Language
VISCII: VIetnamese Standard Code for Information Interchange
VIQR: VIetnamese Quoted-Readable Specification Revision 1.1",
May 1993.