The VIQR Convention

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:

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.


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

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

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