Subtype,Description,Reference
0,Reserved,[RFC5568]
1,Reserved,[RFC5568]
2,RtSolPr,[RFC5568]
3,PrRtAdv,[RFC5568]
4,HI - Deprecated (Unavailable for Assignment),[RFC5568]
5,HAck - Deprecated (Unavailable for Assignment),[RFC5568]
6-255,Unassigned,