[XeTeX] Trouble with displaying word containing 3 conjunct consonants in Devanagari

[Jonathan Kew]

On 29 Sep 2009, at 18:13, Peter Dyballa wrote:

>
> Am 29.09.2009 um 15:54 schrieb Robert Zydenbos:
>
>> Could the difference be because I am using TeXShop as a front end?
>
> No. It's just a piece of software to access the TeX distribution.

Right.

>
> You're not telling the XeTeX backend which script to use. This might  
> produce the seen failures...

No. The example is using Devanagari MT, which is the AAT font shipped  
with OS X. AAT fonts do not require a Script specification, as the  
engine is entirely generic and all the shaping behavior is in the  
font. Adding [Script=...] would cause fontspec to load the font as  
OpenType, and this would completely *disable* the desired features.

The problem sequence originally cited was ङ्ख्ये, which  
fails to display a 3-consonant conjunct, despite the use of the  
Additional Conjuncts feature, although the necessary left-linking form  
of YA is present in the font. Robert's example, on the other hand,  
used the word सङ्ख्या, and in this case the triple  
conjunct does form. The key difference appears to be the immediately- 
following vowel matra: Ravi's example had  े on the य, and this is  
apparently conflicting with the rule to access the left-linking glyph.  
I'd consider this a bug in the AAT tables of the font.

JK