Value,Description,Reference
1,IPv4 address,[RFC3209]
2,IPv6 address,[RFC3209]
3,Label,[RFC6001]
4,Unnumbered Interface ID,[RFC3477]
5,4-byte AS number,[RFC7898][RFC7897]
6,OSPF Area ID,[RFC7898][RFC7897]
7,IS-IS Area ID,[RFC7898][RFC7897]
8-31,Unassigned,
32,Autonomous system number,[RFC3209]
33,"Explicit Exclusion Route
 subobject (EXRS)",[RFC4874]
34,SRLG,[RFC4874]
35,Switching Capability (SC),[RFC6001]
36-37,Unassigned,
38,IPv4 Diversity,[RFC8390]
39,IPv6 Diversity,[RFC8390]