--- a/master/datagram.c	Tue Feb 12 15:30:34 2013 +0100
+++ b/master/datagram.c	Tue Feb 12 15:46:43 2013 +0100
@@ -636,6 +636,8 @@
 /*****************************************************************************/
 
 /** Returns a string describing the datagram type.
+ *
+ * \return Pointer on a static memory containing the requested string.
  */
 const char *ec_datagram_type_string(
         const ec_datagram_t *datagram /**< EtherCAT datagram. */