[XeTeX] How do mapping files affect hyphenation?

[Ulrike Fischer]

Am Fri, 24 Feb 2012 13:40:53 +0100 schrieb Zdenek Wagner:

>> From an old discussion on the mailing list
>> (http://tug.org/mailman/htdig/xetex/2005-November/002842.html) I got
>> the impression that mappings are "invisible" to the hyphenation
>> routine and so I would have expected the translittered text to be
>> hyphenated according the original russian rules but actually it is
>> not hyphenated at all:

> Do the Russian hyphenation patterns contain patterns for the Latin
> script? 

Well I would say, obviously not. 

But my question is if "...font mappings (unlike traditional
TFM-based ligatures) are completely invisible to TeX's line-breaking
process" how comes that the hyphenation routine *knows* that chars
from a latin script are involved? Why doesn't it handle the
hyphenation with the input chars?


-- 
Ulrike Fischer