Re: Bangla: [ZWJ], [VIRAMA] and CV sequences

From: John Cowan (
Date: Wed Oct 08 2003 - 06:04:31 CST

Peter Kirk scripsit:

> I don't understand the specific issues here... But it does seem a rather
> strange design principle that we should expect a text to be displayed
> meaningfully even when the font lacks the glyphs required for proper
> display.

The key term is "necessary". In the Indic scripts, it is a principle
that any instance of a consonant with VIRAMA (the rough equivalent of
schwa quiescens) followed in the same word by another consonant may
be replaced by a ligature of those consonants. However, no ligature
is actually mandatory, and which ligatures are customary depends on the
particular script, the particular language (it's common for some languages
to be written in more than one Indic script), and the particular time
and place of writing. Using fewer ligatures than custom dictates makes
the text look crude, but using too many may render it utterly illegible,
since unfamiliar ligatures are often not recognizable at sight.

Therefore, the Unicode Standard does not encode any Indic ligature,
though it does specify general methods (involving ZWJ and ZWNJ) for
requesting partial or complete ligatures or for prohibiting ligaturing
(and using the explicit VIRAMA appropriate to the script). It is indeed
very much a matter of the font, therefore, which ligatures are possible
and which are not possible.

Disclaimer: I'm no expert on this. These remarks don't apply in their
full generality to Tibetan, and aren't applicable at all to Thai or Lao.

One art / There is                      John Cowan <>
No less / No more             
All things / To do            
With sparks / Galore                     -- Douglas Hofstadter

This archive was generated by hypermail 2.1.5 : Thu Jan 18 2007 - 15:54:24 CST