+struct c_avl_tree_s;
+typedef struct c_avl_tree_s c_avl_tree_t;
+
+struct c_avl_iterator_s;
+typedef struct c_avl_iterator_s c_avl_iterator_t;
+
+/*
+ * NAME
+ * c_avl_create
+ *
+ * DESCRIPTION
+ * Allocates a new AVL-tree.
+ *
+ * PARAMETERS
+ * `compare' The function-pointer `compare' is used to compare two keys. It
+ * has to return less than zero if it's first argument is smaller
+ * then the second argument, more than zero if the first argument
+ * is bigger than the second argument and zero if they are equal.
+ * If your keys are char-pointers, you can use the `strcmp'
+ * function from the libc here.
+ *
+ * RETURN VALUE
+ * A c_avl_tree_t-pointer upon success or NULL upon failure.
+ */
+c_avl_tree_t *c_avl_create (int (*compare) (const void *, const void *));
+
+
+/*
+ * NAME
+ * c_avl_destroy
+ *
+ * DESCRIPTION
+ * Deallocates an AVL-tree. Stored value- and key-pointer are lost, but of
+ * course not freed.
+ */
+void c_avl_destroy (c_avl_tree_t *t);
+
+/*
+ * NAME
+ * c_avl_insert
+ *
+ * DESCRIPTION
+ * Stores the key-value-pair in the AVL-tree pointed to by `t'.
+ *
+ * PARAMETERS
+ * `t' AVL-tree to store the data in.
+ * `key' Key used to store the value under. This is used to get back to
+ * the value again. The pointer is stored in an internal structure
+ * and _not_ copied. So the memory pointed to may _not_ be freed
+ * before this entry is removed. You can use the `rkey' argument
+ * to `avl_remove' to get the original pointer back and free it.
+ * `value' Value to be stored.
+ *
+ * RETURN VALUE
+ * Zero upon success, non-zero otherwise. It's less than zero if an error
+ * occurred or greater than zero if the key is already stored in the tree.
+ */
+int c_avl_insert (c_avl_tree_t *t, void *key, void *value);