Brad Lucier thinks "invert" is a bad lexeme choice for the set-complement
operation. Hence CHAR-SET-INVERT would be better named CHAR-SET-COMPLEMENT.

I agree. Alan Bawden makes three. It is a trivial change. I am making it.
New bits will be available at ftp.ai.mit.edu in 30 minutes, with exactly
this change.
    -Olin