Number,Name,Reference
0,Reserved,[RFC7252]
1,If-Match,[RFC7252][RFC8613]
2,Unassigned,
3,Uri-Host,[RFC7252][RFC8613]
4,ETag,[RFC7252][RFC8613]
5,If-None-Match,[RFC7252][RFC8613]
6,Observe,[RFC7641][RFC8613]
7,Uri-Port,[RFC7252][RFC8613]
8,Location-Path,[RFC7252][RFC8613]
9,OSCORE,[RFC8613]
10,Unassigned,
11,Uri-Path,[RFC7252][RFC8613]
12,Content-Format,[RFC7252][RFC8613]
13,Unassigned,
14,Max-Age,[RFC7252][RFC8516][RFC8613]
15,Uri-Query,[RFC7252][RFC8613]
16,Hop-Limit,[RFC8768]
17,Accept,[RFC7252][RFC8613]
18,Unassigned,
19,Q-Block1,[RFC9177]
20,Location-Query,[RFC7252][RFC8613]
21,EDHOC,[RFC9668]
22,Unassigned,
23,Block2,[RFC7959][RFC8323][RFC8613]
24-26,Unassigned,
27,Block1,[RFC7959][RFC8323][RFC8613]
28,Size2,[RFC7959][RFC8613]
29-30,Unassigned,
31,Q-Block2,[RFC9177]
32-34,Unassigned,
35,Proxy-Uri,[RFC7252][RFC8613]
36-38,Unassigned,
39,Proxy-Scheme,[RFC7252][RFC8613]
40-59,Unassigned,
60,Size1,[RFC7252][RFC8613]
61-127,Unassigned,
128,Reserved,[RFC7252]
129-131,Unassigned,
132,Reserved,[RFC7252]
133-135,Unassigned,
136,Reserved,[RFC7252]
137-139,Unassigned,
140,Reserved,[RFC7252]
141-251,Unassigned,
252,Echo,[RFC9175]
253-257,Unassigned,
258,No-Response,[RFC7967][RFC8613]
259-291,Unassigned,
292,Request-Tag,[RFC9175]
293-2048,Unassigned,
2049,OCF-Accept-Content-Format-Version,[Michael_Koster]
2050-2052,Unassigned,
2053,OCF-Content-Format-Version,[Michael_Koster]
2054,Unassigned,
2055,SCP82-Params,[GPC_SPE_207]
2056-64999,Unassigned,
65000-65535,Reserved for Experimental Use,[RFC7252]