Kind,Length,Meaning,Reference
0,-,End of Option List,[RFC9293]
1,-,No-Operation,[RFC9293]
2,4,Maximum Segment Size,[RFC9293]
3,3,Window Scale,[RFC7323]
4,2,SACK Permitted,[RFC2018]
5,N,SACK,[RFC2018]
6,6,Echo (obsoleted by option 8),[RFC1072][RFC6247]
7,6,Echo Reply (obsoleted by option 8),[RFC1072][RFC6247]
8,10,Timestamps,[RFC7323]
9,2,Partial Order Connection Permitted (obsolete),[RFC1693][RFC6247]
10,3,Partial Order Service Profile (obsolete),[RFC1693][RFC6247]
11,,CC (obsolete),[RFC1644][RFC6247]
12,,CC.NEW (obsolete),[RFC1644][RFC6247]
13,,CC.ECHO (obsolete),[RFC1644][RFC6247]
14,3,TCP Alternate Checksum Request (obsolete),[RFC1146][RFC6247]
15,N,TCP Alternate Checksum Data (obsolete),[RFC1146][RFC6247]
16,,Skeeter,[Stev_Knowles]
17,,Bubba,[Stev_Knowles]
18,3,Trailer Checksum Option,[Subbu_Subramaniam][Monroe_Bridges]
19,18,MD5 Signature Option (obsoleted by option 29),[RFC2385]
20,,SCPS Capabilities,[Keith_Scott]
21,,Selective Negative Acknowledgements,[Keith_Scott]
22,,Record Boundaries,[Keith_Scott]
23,,Corruption experienced,[Keith_Scott]
24,,SNAP,[Vladimir_Sukonnik]
25,,Unassigned (released 2000-12-18),
26,,TCP Compression Filter,[Steve_Bellovin]
27,8,Quick-Start Response,[RFC4782]
28,4,"User Timeout Option (also, other known unauthorized use) [***][1]",[RFC5482]
29,,TCP Authentication Option (TCP-AO),[RFC5925]
30,N,Multipath TCP (MPTCP),[RFC8684]
31,,Reserved (known unauthorized use without proper IANA assignment) [**],
32,,Reserved (known unauthorized use without proper IANA assignment) [**],
33,,Reserved (known unauthorized use without proper IANA assignment) [**],
34,variable,TCP Fast Open Cookie,[RFC7413]
35-68,,Reserved,
69,N,Encryption Negotiation (TCP-ENO),[RFC8547]
70,,Reserved (known unauthorized use without proper IANA assignment) [**],
71-75,,Reserved,
76,,Reserved (known unauthorized use without proper IANA assignment) [**],
77,,Reserved (known unauthorized use without proper IANA assignment) [**],
78,,Reserved (known unauthorized use without proper IANA assignment) [**],
79-171,,Reserved,
172,N,Accurate ECN Order 0 (AccECN0),[RFC-ietf-tcpm-accurate-ecn-34]
173,,Reserved,
174,N,Accurate ECN Order 1 (AccECN1),[RFC-ietf-tcpm-accurate-ecn-34]
175-252,,Reserved,
253,N,"RFC3692-style Experiment 1 (also improperly used for shipping
        products) [*]",[RFC4727]
254,N,"RFC3692-style Experiment 2 (also improperly used for shipping
        products) [*]",[RFC4727]