Updated documentation
diff --git a/user_guide_src/source/general/routing.rst b/user_guide_src/source/general/routing.rst
index 45950fc..6bb5bdb 100644
--- a/user_guide_src/source/general/routing.rst
+++ b/user_guide_src/source/general/routing.rst
@@ -106,6 +106,16 @@
You can also mix and match wildcards with regular expressions.
+Callbacks
+=========
+
+If you are using PHP >= 5.3 you can use callbacks in place of the normal routing
+rules to process the back-references. Example::
+
+ $route['products/([a-z]+)/edit/(\d+)'] = function($product_type, $id){
+ return "catalog/product_edit/" . strtolower($product_type) . "/" . $id;
+ };
+
Reserved Routes
===============