1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| Next Payload  |C|  RESERVED   |         Payload Length        |
+---------------+---------------+-------------------------------+
|  Protocol ID  |   SPI Size    |      Notify Message Type      |
+---------------+---------------+-------------------------------+
|                                                               |
~               Resource Identifier (optional)                  ~
|                                                               |
+-------------------------------+-------------------------------+