Index: MsgDefs.h
===================================================================
diff -u -rc132ce35981454090cab63e3abb69a08eb3b02ea -r43bcdbff752f578fe33ff30ec5cf912454a1b685
--- MsgDefs.h	(.../MsgDefs.h)	(revision c132ce35981454090cab63e3abb69a08eb3b02ea)
+++ MsgDefs.h	(.../MsgDefs.h)	(revision 43bcdbff752f578fe33ff30ec5cf912454a1b685)
@@ -229,6 +229,8 @@
 
     MSG_ID_HD_DEBUG_EVENT = 0xFFF1,                                     ///< HD debug event text to be logged in event log
     MSG_ID_DG_DEBUG_EVENT = 0xFFF2,                                     ///< DG debug event text to be logged in event log
+
+    MSG_ID_ACK_MESSAGE_THAT_REQUIRES_ACK = 0xFFFF,                      ///< Acknowledgment of message that requires acknowledgment
 
     END_OF_MSG_IDS                                                      ///< End of system message IDs
 };