Re: ch ligature in a monospace font

From: Richard Wordingham <>
Date: Fri, 1 Jul 2011 22:26:57 +0100

On Fri, 1 Jul 2011 04:22:59 +0200
Philippe Verdy <> wrote:

> 2011/7/1 Richard Wordingham <>:

> > Its main purpose is to indicate that a sequence of characters do
> > not form a collating unit.  However, if one is using a 'monospace'
> > font to space 'letters' uniformly, i.e. to space collating
> > sequences evenly, then I suggest it is the appropriate character.

> Its main use is in fact to prevent reordering of otherwise canonically
> equivalent sequences involving combining characters.

I wonder if anyone has some statistics on the use of CGJ. Its revised
intended use was to disrupt collating sequences, but you may be right
about its most frequent use being to disrupt canonical reordering. A
few years ago I concluded it wasn't yet safe to type the Welsh place
name Llan͏gollen with CGJ.

> As grapheme clusters should not be broken in the middle by collating
> elements,

A very Eurocentric view!

You're misunderstanding me. The digraph should be encoded <C, H>, and
accidental combinations <C, CGJ, H>. Therefore a 'monospace' font
behaving as JFC wants should bunch <C, H> (a 'ligature') into one cell
and display <C, CGJ, H> using two character cells. I am presuming that
JFC would want ligatures and accidental combinations in normal
proportional fonts to display the same.

> CGJ however MAY have a visual impact on the rendering (notably because
> it helps fixing the relative order of sequences combining characters
> with non-zero combining classes, exactly because these combining
> characters may be positioned relatively to each other). But here I
> don't see any problem od relative ordering.

> In other words, <C,CGJ,H> or
> <C,CGJ,APOS,CGJ,H> would not form the single collating elements really
> needed for Breton.

And I have never intentionally argued otherwise.

Received on Fri Jul 01 2011 - 16:29:26 CDT

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