-@code{nil}. Lisp strings are stored with a trailing NUL
-termination, so no copying (either by the user or the implementation)
-is necessary when passing them to foreign code.
+@code{nil}. Lisp strings of type @code{base-string} are stored with a
+trailing NUL termination, so no copying (either by the user or the
+implementation) is necessary when passing them to foreign code; strings
+of type @code{(simple-array character (*))} are copied by the
+implementation as required.