%...% seems nice to me. I don't think "typability" should be a prime factor in deciding, especially such trivial issues such as shifted-characters (like 75% of punctuation in Makefiles is shifted on most keyboards); readability is _much_ more important (and readability in many cases means not too long, especially for something which is likely to appear multiple times in file lists etc...). I don't like the AM_ variants: automake input files are obviously in the automake language, so it seems silly and redundant to include "AM_".
Incidentally, given the name, I assume the name "reldir" always refers to a relative path? What is it relative to again? If I want to refer to a source file, do I write "$(srcdir)/%reldir%/filename" (as opposed to e.g. "$(top_srcdir)/%reldir%/filename")? ... and "canon_reldir" means the same thing, except canonicalized? [In other words, still always relative, e.g. by converting to an absolute canonical name using some sort of truename function, and then removing the source-directory prefix.] Thanks, -miles -- Cat is power. Cat is peace.