Re: ZWJ and Latin Ligatures (was Re: (long) Re: Chromatic font research)

From: Asmus Freytag (
Date: Mon Jul 01 2002 - 16:08:28 EDT

At 11:34 AM 6/30/02 -0600, John H. Jenkins wrote:
>Remember, Unicode is aiming at encoding *plain text*. For the bulk of
>Latin-based languages, ligation control is simply not a matter of *plain
>text*—that is, the message is still perfectly correct whether ligatures
>are on or off. There are some exceptional cases. The ZWJ/ZWNJ is
>available for such exceptional cases.

Remember also that the simplistic model you present already breaks down for
German, since the same character pair may or may not allow ligation
depending on the content and meaning of the text - features that in the
Unicode model are relegated to *plain* text.

Therefore, I would be much happier if the discussion of the 'standard' case
wasn't as anglo-centric and allowed more directly for the fact that while
fonts are in control of what ligatures are provided, layout engines may be
in control of what and how many optional ligatures to use, the text (!)
must be in control of where ligatures are mandatory or prohibited.

I don't know of a case where a mandatory ligature of two characters is
sometimes prohibited, which means that for all practical cases, mandatory
ligatures, like LAM-ALIF tend to also be handled by the layout engine. But
ligature prohibition is a quite regular feature of German orthography and
any Unicode-based system that intends to provide generic support for Latin
script use, should be able to support it. As the prohibition is on a
case-by-case and word-by-word basis, it has to be marked in the text.


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