Re: XeTeX "tex-text" mapping problem

[Oliver Buerschaper <oliver.buerschaper@mpq.mpg.de>]

>> Hi all,
>>
>> there seems to be a problem with the XeTeX engine and the
>> "mapping:tex-text" feature for OpenType fonts. Try this:
>>
>> ---
>>
>> \usetypescriptfile[type-minion]
>> \usetypescript[minion][uc]
>> \setupbodyfont[minion,13pt]
>>
>> \starttext
>> There is --- without any doubt --- a tiny problem.
>> \stoptext
>>
>> ---
>>
>> together with the attached typescript file. Unfortunately, "---" is
>> not replaced by an em dash :-( Substituting works flawlessly for  
>> plain
>> XeTeX examples. Of course, replacing "---" with the proper Unicode em
>> dash in the above source solves the problem (by avoiding it).
>>
>> Any hints as to what I've done wrong?
> what is mapping=tex-text supposed to do?

As far as I understood it's supposed to map TeX character sequences  
like "--" or "---" onto the corresponding Unicode characters. In fact  
these sequences aren't necessary at all, one could easily type the  
appropriate Unicode dashes in the source code. However, for the  
source editor I use a monospaced font which makes it rather hard to  
distinguish those proper Unicode dashes. I guess the character  
substitution that "mapping=tex-text" performs will extend to few  
other TeX sequences as well ... but definitely not for accented  
characters. Perhaps

http://scripts.sil.org/cms/scripts/page.php? 
site_id=nrsi&item_id=xetex_faq#ligs

might be helpful.

Oliver