Value,Description,Reference
0,IPv4 Explicit NULL Label,[RFC3032]
1,Router Alert Label,[RFC3032]
2,IPv6 Explicit NULL Label,[RFC3032]
3,Implicit NULL Label,[RFC3032]
4-6,Unassigned,
7,Entropy Label Indicator (ELI),[RFC6790]
8-12,Unassigned,
13,Generic Associated Channel Label,[RFC5586]
14,OAM Alert Label,[RFC3429]
15,Extension Label (XL),[RFC7274][RFC9017]