Index: firmware/App/Services/SystemComm.h
===================================================================
diff -u -rd91a24c730aeb5cd7e3eba9ef4eca78e442911f8 -r6a414654391c1729525d55812abbf111ddef7d6a
--- firmware/App/Services/SystemComm.h	(.../SystemComm.h)	(revision d91a24c730aeb5cd7e3eba9ef4eca78e442911f8)
+++ firmware/App/Services/SystemComm.h	(.../SystemComm.h)	(revision 6a414654391c1729525d55812abbf111ddef7d6a)
@@ -39,7 +39,6 @@
     #define PC_MESSAGE_PACKET_SIZE  8
 #endif
 
-#define MSG_ID_ACK                  0xFFFF                                                          ///< Denali message ID for acknowledging received messages (when required).
 #define MSG_ACK_BIT                 0x8000                                                          ///< ACK bit in sequence number that indicates an ACK is required.
 #define MAX_MSG_SEQ_NO              0x7FFF                                                          ///< Maximum sequence number for Denali message (then wraps to 1).
 #define MIN_MSG_SEQ_NO              0x0001                                                          ///< Minimum sequence number for Denali message.