Decimal,Keyword,Version,Reference
0-1,,Reserved,[Jon_Postel][RFC4928]
2-3,,Unassigned,[Jon_Postel]
4,IP,Internet Protocol,[RFC791][Jon_Postel]
5,,Reserved (Historic),"[RFC1819][Moving IP versions 5, 8, and 9 to Historic]"
6,IPv6,Internet Protocol version 6,[RFC8200]
7,,Reserved (Historic),[RFC1475][RFC6814]
8,,Reserved (Historic),"[RFC1621][Moving IP versions 5, 8, and 9 to Historic]"
9,,Reserved (Historic),"[RFC1347][Moving IP versions 5, 8, and 9 to Historic]"
10-14,,Unassigned,[Jon_Postel]
15,,Reserved,[Jon_Postel]