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
  +---------------+---------------+-------+----------------------+
  |     Kind      |   Length=12   |Subtype|      (reserved)      |
  +---------------+---------------+-------+----------------------+
  |                                                              |
  |                 Data Sequence Number (8 octets)              |
  |                                                              |
  +--------------------------------------------------------------+