-/* The symbol N in symbol list L is USED. */
-void symbol_list_n_used_set (symbol_list *l, int n, bool used);
+/* Check whether the node is a border element of a rule. */
+bool symbol_list_null (symbol_list *node);
+
+/** Set the \c \%destructor for \c node as \c code at \c loc. */
+void symbol_list_destructor_set (symbol_list *node,
+ code_props const *destructor);
+
+/** Set the \c \%printer for \c node as \c code at \c loc. */
+void symbol_list_printer_set (symbol_list *node,
+ code_props const *printer);