0   1   2   3   4   5   6   7
              +-------+-------+---------------+
              |       |       |               |
              |  Ver  |   T   |      TKL      |   1 byte
              |       |       |               |
              +-------+-------+---------------+
              |                               |
              |             Code              |   1 byte
              |                               |
              +-------------------------------+
              |                               |
              |                               |
              |                               |
              +-         Message ID          -+   2 bytes
              |                               |
              |                               |
              |                               |
              +-------------------------------+
              \                               \
              /              TKL              /   0-2 bytes
              \          (extended)           \
              +-------------------------------+
              \                               \
              /             Token             /   0-65804 bytes
              \                               \
              +-------------------------------+
              \                               \
              /                               /
              \                               \
              /            Options            /   0 or more bytes
              \                               \
              /                               /
              \                               \
              +---------------+---------------+
              |               |               |
              |      15       |       15      |   1 byte (if payload)
              |               |               |
              +---------------+---------------+
              \                               \
              /                               /
              \                               \
              /            Payload            /   0 or more bytes
              \                               \
              /                               /
              \                               \
              +-------------------------------+