diff --git a/core/modules/system/core.api.php b/core/modules/system/core.api.php
index f138295..06762ac 100644
--- a/core/modules/system/core.api.php
+++ b/core/modules/system/core.api.php
@@ -836,8 +836,12 @@
  *   @link menu Menu and routing system topic @endlink for more information.
  * - cache.bin: Indicates a cache bin service; see the
  *   @link cache Cache topic @endlink for more information.
- * - event_subscriber: Indicates an event subscriber service for routing; see
- *   the @link menu Menu and routing system topic @endlink for more information.
+ * - event_subscriber: Indicates an event subscriber service. Event subscribers
+ *   can be used for dynamic routing and route altering; see the
+ *   @link menu Menu and routing system topic @endlink for more information.
+ *   They can also be used for other purposes; see
+ *   http://symfony.com/doc/current/cookbook/doctrine/event_listeners_subscribers.html
+ *   for more information.
  * - needs_destruction: Indicates that a destruct() method needs to be called
  *   at the end of a request to finalize operations, if this service was
  *   instantiated.
@@ -878,7 +882,6 @@
  * @see \Symfony\Component\DependencyInjection\ContainerInterface
  * @see plugin_api
  * @see menu
- *
  * @}
  */