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/ .