Value,Description,Reference
0,Query,[RFC5971]
1,Response,[RFC5971]
2,Confirm,[RFC5971]
3,Data,[RFC5971]
4,Error,[RFC5971]
5,MA-Hello,[RFC5971]
6-55,Unassigned,
56-63,Reserved for Private/Experimental Use,[RFC5971]
64-127,Reserved,[RFC5971]