[XeTeX] A XeTeX bug or a MiKTeX bug?

Jonathan Kew jonathan_kew at sil.org
Sun Apr 27 17:32:19 CEST 2008

On 27 Apr 2008, at 10:14 am, VAFA KHALIGHI wrote:

> If You use MiKTeX (updated at 2008-02-26) and you typeset persian
> or arabic where you need to have ZERO WIDTH NON-JOINER between some
> words, it does the job well. But if you update MiKTeX (let's say
> today) and do the same as before it makes a gray like vertical line
> between the words that you used to have ZERO WIDTH NON-JIONER
> between them. I actually have put an example on the web and you can
> get it from
>
> I have done this by using the newly updated version of MiKTeX and
> when you look at the pdf file, you will observe the those gray
> vertical lines that I was talking about.
>
> So is this a XeTeX bug or a MiKTeX bug?
>

The line you are seeing is the glyph provided for U+200C (zero width
non-joiner) in the Roya font. In earlier versions of the ICU layout
library, these glyphs were filtered out and never displayed, but as a
result of some changes in v3.8 they now remain in the text, and so if
the font has a visible glyph rather than a zero-width, blank one, you
see it on the page.

http://bugs.icu-project.org/trac/ticket/6023 shows that this is
considered an ICU layout bug, and the behavior has been changed
again. I have just applied the patch from that ticket to the xetex
repository, so when MikTeX (or other distributions) is updated to v.
0.998.1, the problem should go away.

One possible solution in the meantime is to implement ZWNJ at the
macro level; a simple version might be

\catcode"200C=\active
\def^^^^200c{\hskip0pt\relax}

though if you need it to be "robust" in LaTeX terms, a bit more care
may be needed.

JK

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://tug.org/pipermail/xetex/attachments/20080427/ef9dd57f/attachment-0001.html