--- a/master/sdo_request.c	Tue Feb 12 15:30:34 2013 +0100
+++ b/master/sdo_request.c	Tue Feb 12 15:46:43 2013 +0100
@@ -85,6 +85,8 @@
 /** Copy another SDO request.
  *
  * \attention Only the index subindex and data are copied.
+ *
+ * \return Zero on success, otherwise a negative error code.
  */
 int ec_sdo_request_copy(
         ec_sdo_request_t *req, /**< SDO request. */