Index: firmware/App/Services/Reservoirs.h
===================================================================
diff -u -r62ee40b55ed96eb0de1c0f05455eb986f76c1842 -r8059b3b67364c3593091a23266f33186430ffe26
--- firmware/App/Services/Reservoirs.h	(.../Reservoirs.h)	(revision 62ee40b55ed96eb0de1c0f05455eb986f76c1842)
+++ firmware/App/Services/Reservoirs.h	(.../Reservoirs.h)	(revision 8059b3b67364c3593091a23266f33186430ffe26)
@@ -39,26 +39,34 @@
 } 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 **********
 
 void initReservoirs( void );
 void execReservoirs( void );
 
-BOOL setActiveReservoirCmd( RESERVOIR_ID_T resID );    // handle switch reservoirs command from HD
-BOOL startFillCmd( U32 fillToVolMl );                  // handle fill command from HD
-BOOL stopFillCmd( void );                              // handle stop fill command from HD
-BOOL startDrainCmd( DRAIN_CMD_T drainCmd );            // handle drain command from HD
-BOOL stopDrainCmd( void );                             // handle stop drain command from HD
-BOOL startTrimmerHeaterCmd( void );                    // handle start trimmer heater control command from HD
-BOOL stopTrimmerHeaterCmd( void );                     // handle stop trimmer heater control command from HD
+void setActiveReservoirCmd( RESERVOIR_ID_T resID );    // handle switch reservoirs command from HD
+void startFillCmd( U32 fillToVolMl );                  // handle fill command from HD
+void stopFillCmd( void );                              // handle stop fill command from HD
+void startDrainCmd( DRAIN_CMD_T drainCmd );            // handle drain command from HD
+void stopDrainCmd( void );                             // handle stop drain command from HD
 
 RESERVOIR_ID_T getInactiveReservoir( void );
 BOOL hasTargetFillVolumeBeenReached( RESERVOIR_ID_T reservoirId );