@defun string-to-unibyte string
This function returns a unibyte string containing the same sequence of
-characters as @var{string}. It signals an error if @var{string}
-contains a non-@acronym{ASCII} character. If @var{string} is a
-unibyte string, it is returned unchanged. Use this function for
-@var{string} arguments that contain only @acronym{ASCII} and eight-bit
-characters.
+characters as @var{string}. If @var{string} is a unibyte string, it
+is returned unchanged. Otherwise, @acronym{ASCII} characters and
+characters in the @code{eight-bit} charset are converted to their
+corresponding byte values. Use this function for @var{string}
+arguments that contain only @acronym{ASCII} and eight-bit characters;
+the function signals an error if any other characters are encountered.
@end defun
@defun byte-to-string byte