[XeTeX] Incorrect rendering of Vedic Sanskrit accents

[David M. Jones]

Mike Maxwell's original post hasn't shown up here yet, so I'm lumping
two responses together.

> Date: Fri, 22 May 2015 12:24:49 -0600
> From: Bobby de Vos <devos.bobby at gmail.com>
> Reply-To: "XeTeX (Unicode-based TeX) discussion." <xetex at tug.org>
> 
> On 2015-05-22 10:49, maxwell wrote:
> > On 2015-05-22 10:14, David M. Jones wrote:
> >> ...
> >> P.S. There's actually a third class of bug that is clearly visible in
> >> the table at the top of my document, but which I didn't mention
> >> explicitly: XeTeX won't typeset one of the Devanagari combining
> >> characters in isolation without adding a prothetic dotted circle
> >> (U+25CC).
> >
> > I was waiting for someone who knows more about this than I do to
> > answer, but I'll display my ignorance.
> >
> > Afaik that's not a bug, that's the way combining characters are
> > *supposed* to render when they don't have any character to combine

This is, I think, debatable, as shown by the fact that XeTeX does
*not* add the dotted circle for any of the combining diacritical in
the 0300 block, and LuaTeX doesn't add them for the Devanagari marks.
So at the very least, this is a matter of consistency.

> > with.  There's a way to prevent that; I _think_ it's to precede the
> > combining character by a non-breaking space (U+00A0).  But I haven't
> > tried that.

You're correct: that is the suggested Unicode coding and it does in
fact work. (I thought I tried it before and it didn't work, but either
I'm misremembering or it was before I upgraded to the latest XeTeX.)

> Some minority languages (that is, not the dominate language using a
> particular script) often use combining marks in ways not envisioned in
> order to extend the script to cover all the sounds in the minority
> language. So for those minority languages, having a dotted circle show
> up is not very helpful.

Arguably, it never is -- if you want a dotted circle, you can add it
yourself, whereas it's not at all unusual to want to show combining
marks in isolation in, say, textbooks.

But I admit this is an edge case, which is probabably why I decided
against drawing attention to it in my original sourceforge bug report.
I wish I had stuck to my earlier resolve.

Cheers,
David.

> Bobby
> 
> -- 
> Bobby de Vos
> /devos.bobby at gmail.com/
> 
> 
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