Currently, (subsidiary-coding-system) returns its parameter if it has not an autodetect property: (subsidiary-coding-system (find-coding-system 'undecided) 'crlf) =>> #<coding_system undecided-dos> (subsidiary-coding-system (find-coding-system 'undecided-unix) 'crlf) =>> #<coding_system undecided-unix> I might be missing something obvious, but I cannot easily deduce a coding system different from a given one only by eol-type. I think either this function should be changed so that it finds a coding system even when given a no-autodecect coding system or, if this change is going to break anything, a new function must be introduced which does what I want. Again if only I am not missing "the right" way of doing this. Big K