multibyte strings should not be noticeable, since inserting them in
unibyte buffers converts them to unibyte automatically. However, if
this does make a difference, you can force a particular Lisp file to be
-interpreted as unibyte by writing @samp{-*-coding: raw-text;-*-} in a
+interpreted as unibyte by writing @samp{-*-unibyte: t;-*-} in a
comment on the file's first line. With that designator, the file will
be unconditionally be interpreted as unibyte, even in an ordinary
multibyte Emacs session.