Value,Attribute Type,Format,Reference
0-13,Reserved,,[RFC7296]
14,Key Length (in bits),TV,[RFC7296]
15-17,Reserved,,[RFC7296]
18,Signature Algorithm Identifier,TLV,[RFC-ietf-ipsecme-g-ikev2-21]
19-16383,Unassigned,,
16384-32767,Reserved for Private Use,,[RFC7296]