diff -r caeb4c8b5487 -r ba6b8e38d90e Model/DocumentInterface.php
--- a/Model/DocumentInterface.php	Wed Dec 14 23:53:37 2011 +0100
+++ b/Model/DocumentInterface.php	Mon Dec 19 17:50:04 2011 +0100
@@ -76,5 +76,9 @@
     */
     function getCreatedAt();
     
+    /**
+     * __toString magic method
+     */
+    function __toString();
             
 }