Index: MessageSupport.h
===================================================================
diff -u -r9512aac6feeb1379d6d425361fa78d58f75c86f6 -rb8c0a53bcfa6be12c305761b0b1b5c79e97b55ca
--- MessageSupport.h	(.../MessageSupport.h)	(revision 9512aac6feeb1379d6d425361fa78d58f75c86f6)
+++ MessageSupport.h	(.../MessageSupport.h)	(revision b8c0a53bcfa6be12c305761b0b1b5c79e97b55ca)
@@ -19,6 +19,7 @@
 #define __MESSAGESUPPORT_H__
 
 #include "CommBuffers.h"
+#include "MsgDefs.h"
 
 /**
  *  @defgroup MessageSupport MessageSupport
@@ -29,6 +30,38 @@
  *  @{
  */
 
+// ********** public definitions ******************
+
+#define MAX_MSG_PAYLOAD_SIZE    250                                         ///< Bytes
+#define MESSAGE_OVERHEAD_SIZE   (sizeof(MESSAGE_HEADER_T) + sizeof(U08))    ///< Byte size of a message's overhead (fixed at 6 bytes).
+
+#pragma pack(push,1)
+
+/// Record structure for message header.
+typedef struct
+{
+    S16 seqNo;                                          ///< Sequence number (and ACK required bit) of message
+    U16 msgID;                                          ///< ID of message
+    U08 payloadLen;                                     ///< Length of payload in bytes
+} MESSAGE_HEADER_T;
+
+/// Record structure for a message (header + payload).
+typedef struct
+{
+    COMM_BUFFER_T    in_buffer;                         ///< Message received into this channel buffer
+    MESSAGE_HEADER_T hdr;                               ///< Message header
+    U08              payload[ MAX_MSG_PAYLOAD_SIZE ];   ///< Message payload
+} MESSAGE_T;
+
+/// Record structure for a wrapped message (message + CRC).
+typedef struct
+{
+    MESSAGE_T        msg;                               ///< Message
+    U08              crc;                               ///< Message CRC
+} MESSAGE_WRAPPER_T;
+
+#pragma pack(pop)
+
 // ********** public function prototypes **********
 
 BOOL broadcastData( MSG_ID_T msgID, COMM_BUFFER_T buffer, U08* dataPtr, U32 length );