Value,Description,Reference
0x00,Reserved,[RFC5974]
0x01,RESERVE,[RFC5974]
0x02,QUERY,[RFC5974]
0x03,RESPONSE,[RFC5974]
0x04,NOTIFY,[RFC5974]
0x05-0xEF,Unassigned,
0xF0-0xFF,Reserved for Experimental/Private Use,[RFC5974]