On my installation LuaTeX can't use fontspec.sty, because it requires XeTeX.
When browsing the manual for references to XeTeX, one finds three:
the extension to full Unicode (the \U prefix) is compatible with XETEX.
New primitives that are compatible with XETEX:
consistent with its changed meaning in XETEX.
This seems to suggest that compatibility with XeTeX is a design goal.
True or false?
Dirk
