Directory macros/unicodetex

 README.txt for CTAN:/macros/unicodetex/ :

 This directory tree is meant for packages that work with
 _either_ of the “modern” TeX engines XeTeX or LuaTeX,
 but _not_ with the “traditional” TeX engines TeX and pdfTeX.

 For packages that require LuaTeX (and will work with _none_
 of the other engines!) go to CTAN:/macros/luatex/ .

 For packages that require XeTeX (and will work with _none_
 of the other engines!) go to CTAN:/macros/xetex/ .