The VIQR Convention

VIQR stands for VIetnamese Quoted-Readable, which is a convention to write Vietnamese letters using 7-bit ASCII. This convention arises from the need to exchange Vietnamese messages in 7-bit environments such as email or the soc.culture.vietnamese newsgroup in the Internet. For this reason VIQR is also known as Vietnet convention.

The Viet-Std Group formally finalized the VIQR convention in 1992. As an introduction, consider this message written in the VIQR convention:

To^i ye^u tie^'ng nu+o+'c to^i tu+` khi mo+'i ra ddo+`i\.

It can be seen that the intent is to represent Vietnamese diacritical marks (da^'u phu.) as ASCII characters that suggest the shape of the original accents or tonemarks.

According to the VIQR standard, the following characters are subject to interpretation as Vietnamese diacritical marks:

    ================================================================
    Diacritic   Char  ASCII Code          Da^'u      Example        
    ----------------------------------------------------------------
    breve        (    0x28, left paren    tra(ng     ba(n khoa(n    
    circumflex   ^    0x5E, caret         mu~        ho^m nay       
    horn         +    0x2B, plus sign     mo'c       Qui Nho+n      
                                                                    
    acute        '    0x27, apostrophe    sa('c      La'i Thie^u    
    grave        `    0x60, backquote     huye^`n    Bi`nh Du+o+ng  
    hook above   ?    0x3F, question      ho?i       Thu?  DDu+'c   
    tilde        ~    0x7E, tilde         nga~       di~ va~ng      
    dot below    .    0x2E, period        na(.ng     ho.c ta^.p     
    ================================================================
    In addition, dd stands for d bar and DD stands for D bar.

The VIQR standard specifies that a character is interpreted as a diacritic if and only if it can combine with the previous letter into a legal Vietnamese character. To prevent combination the character must be preceded by an escape character, which is usually the backslash ( \ ) character.

Examples:

• O+ is a legal Vietnamese letter (O horn), hence + is a diacritic mark.
• A+ is not a legal Vietnamese letter, hence + is a stand-alone plus sign, not a diacritic mark.
• ... mo+'i ra ddo+`i\. -- the backslash indicates the following period is a punctuation, not a dot-below diacritic.
• Anh ddi dda^u\? -- the backslash indicates the following question mark is a punctuation, not a hook-above diacritic.

The complete VIQR standard specifies that a text stream is always tagged as being in Vietnamese mode, English mode, or Literal mode:

• A sequence \V signifies that the text following it is in Vietnamese mode and must be interpreted according to the VIQR convention for diacritic marks.
• A sequence \M signifies that the text following it is in English mode. Only sequences beginning with a backslash are interpreted according to the VIQR convention for diacritic marks.
• A sequence \L signifies that the text following it is in Literal mode. No interpretation applies, except for the switching mode sequences \V, \M, \L, and their lower-case counterparts.

For complete information, please read the official Viet-Std report published in 1992 at

http://vietstd.sf.net.

Updated: December 17, 2014 -- Viet-Std Group