Re: ZWJ, ZWNJ and Markup languages.

From: Martin J. Dürst <>
Date: Sat, 28 Nov 2015 10:42:15 +0900

On 2015/11/28 04:55, Plug Gulp wrote:

> The Unicode standard 8.0 states in chapter 23, section titled "Cursive
> Connection and Ligatures"(printed page #814, PDF page #850) that:
> "The zero width joiner and non-joiner characters are designed for use
> in plain text; they should not be used where higher-level ligation and
> cursive control is available. (See Uni-code Technical Report #20,
> “Unicode in XML and Other Markup Languages,” for more information.) "
> I went through TR#20 and did not find any mention that ZWJ and ZWNJ
> are not suitable for use with markup languages. On the contrary, ZWJ
> and ZWNJ are listed in TR#20 under section 4 titled "Format Characters
> Suitable for Use with Markup".
> So are ZWJ and ZWNJ characters suitable for use with markup languages
> such as HTML and XML?

They are indeed suitable for use with markup languages. They are so
suitable that they are already provided as entities in RFC 2070, which
is now historic, and from there on through HTML 4.0 and onwards. Please

I'm not sure why Unicode 8.0 has the text it has; at the least, this
should be toned down somewhat to say "they may be replaced by
higher-level ligation and cursive control mechanisms if available".
Thanks for finding this!

The main reason for this is that these characters apply at a single
point; creating markup such as <zwj/> and <zwnj/> would not give any
advantages over &zwj;/&zwnj;.

Markup is at its best when it can be applied to nested spans of text. It
is not inconcievable that something like <do_not_ligate_inside>...
</do_not_ligate_inside> could occasionally be useful, but I have
difficulties immagining a use case of the top of my head.

I'll file a bug report with the content of this email.

Regards, Martin.
Received on Fri Nov 27 2015 - 19:43:06 CST

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