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\.
(Tôi yêu tiếng nước tôi từ khi mới ra đời.)
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.\V signifies that the text following
it is in Vietnamese mode and must be interpreted according to the VIQR
convention for diacritic marks.\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.\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.