Index: firmware/App/Services/Reservoirs.h
===================================================================
diff -u -rf401094683b7f3b082c41493f1a217c28a331e5c -rb549c9d87eb01cf1afee74e9fc1e41b3731bdca4
--- firmware/App/Services/Reservoirs.h	(.../Reservoirs.h)	(revision f401094683b7f3b082c41493f1a217c28a331e5c)
+++ firmware/App/Services/Reservoirs.h	(.../Reservoirs.h)	(revision b549c9d87eb01cf1afee74e9fc1e41b3731bdca4)
@@ -39,12 +39,22 @@
 } RESERVOIR_ID_T;
 
 #pragma pack(push,1)
-/// Enumeration of drain command.
+
+/// Drain command data structure.
 typedef struct
 {
     U32 targetVolume;       ///< Target volume to drain to (in mL)
     BOOL tareLoadCell;      ///< Flag to tare load call
 } DRAIN_CMD_T;
+
+/// DG command response data record.
+typedef struct
+{
+    U32 commandID;          ///< The command DG is responding to
+    BOOL rejected;          ///< Flag indicates if the command has been rejected
+    U32 rejectCode;         ///< Reason code for rejecting the command
+} DG_CMD_RESPONSE_T;
+
 #pragma pack(pop)
 
 // ********** public function prototypes **********