Re: Unicode biwidth fonts

From: Markus Kuhn (
Date: Tue Dec 08 1998 - 19:09:08 EST

Jungshik Shin wrote on 1998-12-08 19:31 UTC:
> One remaining issue to resolve is which charcters are half-width and
> which are full-width. In CJK cases, it's clear-cut, but in UTF-8, it's
> not so. I guess it would be all right if vi and terminal emulator can
> agree with each other on the character width.

I guess the best convention is to declare the characters of category W
and F in Unicode Draft Technical Report #11 <
unicode/reports/dtr11.html>, i.e. the characters 1100..11F9, 3000..30FE,
3131..33FE, 4E00..9FA5, AC00..D7A3, E000..E757, F900..FA2D, FE30..FE44,
FE49..FE52, FE54..FE6B, FF01..FF5E, FFE0..FFE6, to be wide characters
occopying the space of 2 ASCII characters, and all the remaining Unicode
characters are as wide as ASCII characters in a monospaced font.

What I don't like about the tables in DTR11 is that class X is so large.
If there is a single code point free in the middle of a large number of
W characters, then this code point should be reserved to future W
characters and should not be listed as unassigned. The distinction
between narrow and wide characters should be possible efficiently in
software in an if statement that fits on three lines in C without a
table lookup. The given intervals should be a bit more generous to
simplify implementation.


Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK
Email: mkuhn at,  WWW: <>

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