When using input like the following with xetex then harfbuzz kicks in and one would always get the good looking precomposed U+1EA0 for the A and the decomposed B+U+0323 for the B. With context (and lualatex) one get a rather bad looking -- as the dot is misplaced -- output for the A^^^^0323 input and no output at all for ^^^^1e04. As the coverage for precomposed glyphs varies a lot across fonts this is rather a nuisance. Is there a way to get the fontloader (also the one used by luaotfload) to do a similar substituation as done by harfbuzz? \starttext \catcode`\^= 7 Ạ A^^^^0323 %decomposed input -> U+1EA0 with xetex Ạ ^^^^1ea0 %precomposed input Ḅ B^^^^0323 %decomposed input ^^^^1e04 %precomposed input -> B+U+0323 with xetex \stoptext (I added the ^^-notation to avoid problems with copy&paste) -- Ulrike Fischer http://www.troubleshooting-tex.de/