If the user types @key{RET} in an empty minibuffer, this function
returns an empty string, regardless of the value of
@var{require-match}. This is, for instance, how the user can make the
-current buffer visit no file using @code{M-x set-visited-file-name}.
+current buffer visit no file using @kbd{M-x set-visited-file-name}.
If @var{predicate} is non-@code{nil}, it specifies a function of one
argument that decides which file names are acceptable completion