Hi all, I'm running into a problem, but maybe not all hope is lost. For my Greek stuff, I will sometimes need a "dotbelowcomb" accent. Only very few fonts have that, but no problem, in mkiv, I can simply take that from a follback font: \definefontfallback [GreekFallback] [name:texgyretermesregular] [0x0323] [force=no,check=no] Now I would like to remap the exclam character to this dotbelowcom. Again, no problem: with a fea file, I can write a sub rule sub exclam by dotbelowcomb but I can't combine both approaches: if the font doesn't have the character, I get an error about "invalid glyph index." In good old pdftex, it was possible to define a virtual font for such occasions, and I seem to remember that there's something similar in mkiv, but I'm unsure how it can be done. Any pointers? Thanks, and all best Thomas