-/* Call this first to get a handle to pass to other functions. */
-extern cpp_reader *cpp_create_reader PARAMS ((enum c_lang));
+/* Call this first to get a handle to pass to other functions. If you
+ want cpplib to manage its own hashtable, pass in a NULL pointer.
+ Or you can pass in an initialised hash table that cpplib will use;
+ this technique is used by the C front ends. */
+extern cpp_reader *cpp_create_reader PARAMS ((struct ht *,
+ enum c_lang));