Laurent Siebenmann writes:
 > I was surprised to hear that the use of one TeX hyphenation trie
 > for French (say) is incompatible with the use of several font encodings,
 > say T1 and the Y&Y encoding.

as far as i (quickly) read that list i've never found that.
At that time the French patterns file is independant of any font
encoding widely used to typeset French documents. Do i missed

One point can differ from, let's say, T1 vs OT1 is the hyphenation
char. That's the reason why Bernd Raichle designed hypht1.tex.
To easily include this file at initex i modified few time ago the
loading mechanism used in French Pro to accept the font encoding as a
suplementary argument in language.dat file. Defaultly this is t1
and hyph<encoding>.tex is loaded if it exists. To avoid loading
a "-" should be provided.