Hi Ross, > No, it is not specific to MikTeX. > I get the same with > XeTeXk, Version 3.1415926-2.2-0.999.7 (Web2C 7.5.6) > on MacOS X. > > Presumably the primitive comes with an even later version > of XeTeX itself. I think \newXeTeXintercharclass is a macro defined in xelatex.ini. Are you using an old xelatex.ini? Thanks, Akira