Concise Binary Object Representation (CBOR) Tags

Created
2013-09-19
Last Updated
2026-09-18
Available Formats

XML
HTML
TXT

Registries Included Below

CBOR Tags

Expert(s)
Christian Amsüss, Thomas Fossati, Francesca Palombini, Carsten Bormann (backup)
Reference
[RFC 8949]
Note
All registration requests must include the template from [RFC 8949].
Available Formats

CSV
Range Registration Procedures
0-23 Standards Action
24-32767 Specification Required
32768-18446744073709551615 First Come First Served
Tag Data Item Semantics Reference Template
0 text string Standard date/time string; see Section 3.4.1 [RFC 8949]
1 integer or float Epoch-based date/time; see Section 3.4.2 [RFC 8949]
2 byte string Unsigned bignum; see Section 3.4.3 [RFC 8949]
3 byte string Negative bignum; see Section 3.4.3 [RFC 8949]
4 array Decimal fraction; see Section 3.4.4 [RFC 8949]
5 array Bigfloat; see Section 3.4.4 [RFC 8949]
6-15 Unassigned
16 COSE_Encrypt0 COSE Single Recipient Encrypted Data Object [RFC 9052]
17 COSE_Mac0 COSE Mac w/o Recipients Object [RFC 9052]
18 COSE_Sign1 COSE Single Signer Data Object [RFC 9052]
19 COSE_Countersignature COSE standalone V2 countersignature [RFC 9338]
20 Unassigned
21 (any) Expected conversion to base64url encoding; see Section 3.4.5.2 [RFC 8949]
22 (any) Expected conversion to base64 encoding; see Section 3.4.5.2 [RFC 8949]
23 (any) Expected conversion to base16 encoding; see Section 3.4.5.2 [RFC 8949]
24 byte string Encoded CBOR data item; see Section 3.4.5.1 [RFC 8949]
25 unsigned integer reference the nth previously seen string [http://cbor.schmorp.de/stringref][Marc_A._Lehmann]
26 array Serialised Perl object with classname and constructor arguments [http://cbor.schmorp.de/perl-object][Marc_A._Lehmann]
27 array Serialised language-independent object with type name and constructor arguments [http://cbor.schmorp.de/generic-object][Marc_A._Lehmann]
28 multiple mark value as (potentially) shared [http://cbor.schmorp.de/value-sharing][Marc_A._Lehmann]
29 unsigned integer reference nth marked value [http://cbor.schmorp.de/value-sharing][Marc_A._Lehmann]
30 array Rational number [http://peteroupc.github.io/CBOR/rational.html][Peter_Occil]
31 Undefined (0xf7) Absent value in a CBOR Array [https://github.com/svaarala/cbor-specs/blob/master/cbor-absent-tag.rst][Sami_Vaarala]
32 text string URI; see Section 3.4.5.3 [RFC 8949]
33 text string base64url; see Section 3.4.5.3 [RFC 8949]
34 text string base64; see Section 3.4.5.3 [RFC 8949]
35 UTF-8 string Regular expression; see Section 2.4.4.3 [RFC 7049]
36 text string MIME message; see Section 3.4.5.3 [RFC 8949]
37 byte string Binary UUID ([RFC9562, Section 4]) [https://github.com/lucas-clemente/cbor-specs/blob/master/uuid.md][Lucas_Clemente]
38 array Language-tagged string [RFC9290, Appendix A]
39 multiple Identifier [https://github.com/lucas-clemente/cbor-specs/blob/master/id.md][Lucas_Clemente]
40 array of two arrays [1] Multi-dimensional Array, row-major order [RFC 8746]
41 array Homogeneous Array [RFC 8746]
42 byte string IPLD content identifier [https://github.com/ipld/cid-cbor/][Volker_Mische]
43 text string YANG bits datatype; see Section 6.7. [RFC 9254]
44 text string YANG enumeration datatype; see Section 6.6. [RFC 9254]
45 unsigned integer or text string YANG identityref datatype; see Section 6.10. [RFC 9254]
46 unsigned integer or text string or array YANG instance-identifier datatype; see Section 6.13. [RFC 9254]
47 unsigned integer YANG Schema Item iDentifier (sid); see Section 3.2. [RFC 9254]
48 byte string IEEE MAC Address [RFC 9542]
49-51 Unassigned
52 byte string or array IPv4, [prefixlen,IPv4], [IPv4,prefixpart] [RFC 9164]
53 Unassigned
54 byte string or array IPv6, [prefixlen,IPv6], [IPv6,prefixpart] [RFC 9164]
55-57 Unassigned
58 (any) An array claim element intended to be redacted, or a map key whose key and value are intended to be redacted. (TEMPORARY - registered 2025-12-09, expires 2026-12-09) [draft-ietf-spice-sd-cwt-06, Section 11.1]
59 Unassigned
60 byte string A selective disclosure redacted (array) claim element. (TEMPORARY - registered 2025-12-09, expires 2026-12-09) [draft-ietf-spice-sd-cwt-06, Section 5.1]
61 CBOR Web Token (CWT) CBOR Web Token (CWT) [RFC 8392][Michael_B._Jones]
62 uint .gt 0 A marker of a location in a map or an array where a decoy is intended to be inserted. (TEMPORARY - registered 2026-01-27, expires 2027-01-27) [draft-ietf-spice-sd-cwt-06, Section 11.2]
63 byte string Encoded CBOR Sequence [RFC 8742] [draft-bormann-cbor-notable-tags-02, Section 2.1]
64 byte string uint8 Typed Array [RFC 8746]
65 byte string uint16, big endian, Typed Array [RFC 8746]
66 byte string uint32, big endian, Typed Array [RFC 8746]
67 byte string uint64, big endian, Typed Array [RFC 8746]
68 byte string uint8 Typed Array, clamped arithmetic [RFC 8746]
69 byte string uint16, little endian, Typed Array [RFC 8746]
70 byte string uint32, little endian, Typed Array [RFC 8746]
71 byte string uint64, little endian, Typed Array [RFC 8746]
72 byte string sint8 Typed Array [RFC 8746]
73 byte string sint16, big endian, Typed Array [RFC 8746]
74 byte string sint32, big endian, Typed Array [RFC 8746]
75 byte string sint64, big endian, Typed Array [RFC 8746]
76 byte string (reserved) [RFC 8746]
77 byte string sint16, little endian, Typed Array [RFC 8746]
78 byte string sint32, little endian, Typed Array [RFC 8746]
79 byte string sint64, little endian, Typed Array [RFC 8746]
80 byte string IEEE 754 binary16, big endian, Typed Array [RFC 8746]
81 byte string IEEE 754 binary32, big endian, Typed Array [RFC 8746]
82 byte string IEEE 754 binary64, big endian, Typed Array [RFC 8746]
83 byte string IEEE 754 binary128, big endian, Typed Array [RFC 8746]
84 byte string IEEE 754 binary16, little endian, Typed Array [RFC 8746]
85 byte string IEEE 754 binary32, little endian, Typed Array [RFC 8746]
86 byte string IEEE 754 binary64, little endian, Typed Array [RFC 8746]
87 byte string IEEE 754 binary128, little endian, Typed Array [RFC 8746]
88-95 Unassigned
96 COSE_Encrypt COSE Encrypted Data Object [RFC 9052]
97 COSE_Mac COSE MACed Data Object [RFC 9052]
98 COSE_Sign COSE Signed Data Object [RFC 9052]
99 array CRI Reference [RFC-ietf-core-href-29]
100 Unsigned or negative integer Number of days since the epoch date 1970-01-01 [RFC 8943]
101 array [uint, any] alternatives as given by the uint + 128; see Section 9.1 [draft-bormann-cbor-notable-tags-07]
102 Unassigned
103 array Geographic Coordinates [https://github.com/allthingstalk/cbor/blob/master/CBOR-Tag103-Geographic-Coordinates.md][Danilo_Vidovic]
104 multiple Geographic Coordinate Reference System WKT or EPSG number [draft-clarke-cbor-crs-01]
105-106 Unassigned
107 map SUIT_Envelope as defined in Appendix A of [RFC-ietf-suit-manifest-34] [RFC-ietf-suit-manifest-34]
108 byte string Expected conversion to base16 encoding (lowercase) [draft-bormann-cbor-notable-tags-12, Section 2.1, Paragraph 2, Item 2]
109 Unassigned
110 byte string, array, or map relative object identifier (BER encoding); SDNV [RFC 6256] sequence [RFC 9090]
111 byte string, array, or map object identifier (BER encoding) [RFC 9090]
112 byte string, array, or map object identifier (BER encoding), relative to 1.3.6.1.4.1 [RFC 9090]
113-119 Unassigned
120 multiple Internet of Things Data Point [https://github.com/allthingstalk/cbor/blob/master/CBOR-Tag120-Internet-of-Things-Data-Points.md][Danilo_Vidovic]
121-127 any alternatives 0..6, 1+1 encoding; see Section 9.1 [draft-bormann-cbor-notable-tags-07]
128-199 Unassigned
200 multiple Gordian Envelope [draft-mcnally-envelope-05]
201 any enclosed dCBOR [draft-mcnally-deterministic-cbor-10]
202-255 Unassigned
256 multiple mark value as having string references [http://cbor.schmorp.de/stringref][Marc_A._Lehmann]
257 byte string Binary MIME message [http://peteroupc.github.io/CBOR/binarymime.html][Peter_Occil]
258 array Mathematical finite set [https://github.com/input-output-hk/cbor-sets-spec/blob/master/CBOR_SETS.md][Alfredo_Di_Napoli]
259 map Map datatype with key-value operations (e.g. `.get()/.set()/.delete()`) [https://github.com/shanewholloway/js-cbor-codec/blob/master/docs/CBOR-259-spec--explicit-maps.md][Shane_Holloway]
260 byte string Network Address (IPv4 or IPv6 or MAC Address) (DEPRECATED in favor of 52 and 54 for IP addresses) [http://www.employees.org/~ravir/cbor-network.txt][Ravi_Raju][RFC 9164]
261 map (IPAddress + Mask Length) Network Address Prefix (IPv4 or IPv6 Address + Mask Length) (DEPRECATED in favor of 52 and 54 for IP addresses) [https://github.com/toravir/CBOR-Tag-Specs/blob/master/networkPrefix.md][Ravi_Raju][RFC 9164]
262 byte string Embedded JSON Object [https://github.com/toravir/CBOR-Tag-Specs/blob/master/embeddedJSON.md][Ravi_Raju]
263 byte string Hexadecimal string [https://github.com/toravir/CBOR-Tag-Specs/blob/master/hexString.md][Ravi_Raju]
264 array Decimal fraction with arbitrary exponent [http://peteroupc.github.io/CBOR/bigfrac.html][Peter_Occil]
265 array Bigfloat with arbitrary exponent [http://peteroupc.github.io/CBOR/bigfrac.html][Peter_Occil]
266 text string Internationalized resource identifier (IRI) [https://peteroupc.github.io/CBOR/iri.html][Peter_Occil]
267 text string Internationalized resource identifier reference (IRI reference) [https://peteroupc.github.io/CBOR/iri.html][Peter_Occil]
268 array Extended decimal fraction [https://peteroupc.github.io/CBOR/extended.html][Peter_Occil]
269 array Extended bigfloat [https://peteroupc.github.io/CBOR/extended.html][Peter_Occil]
270 array Extended rational number [https://peteroupc.github.io/CBOR/extended.html][Peter_Occil]
271 DDoS Open Threat Signaling (DOTS) signal channel object DDoS Open Threat Signaling (DOTS) signal channel object, as defined in [RFC 9132] [RFC 9132]
272 byte string Non-UTF-8 CESU-8 string [https://github.com/svaarala/cbor-specs/blob/master/cbor-nonutf8-string-tags.rst][Sami_Vaarala]
273 byte string Non-UTF-8 WTF-8 string [https://github.com/svaarala/cbor-specs/blob/master/cbor-nonutf8-string-tags.rst][Sami_Vaarala]
274 byte string Non-UTF-8 MUTF-8 string [https://github.com/svaarala/cbor-specs/blob/master/cbor-nonutf8-string-tags.rst][Sami_Vaarala]
275 map (major type 5) Map contains only keys that are of type Text String (major type 3) [https://github.com/ecorm/cbor-tag-text-key-map][Emile_Cormier]
276 byte string ERIS binary read capability [http://purl.org/eris]
277 byte string Universal Geographical Area Description (GAD) shape; see Section 5 [TS 23.032][Mathew_Meins]
278 byte string Universal Geographical Area Description (GAD) description of velocity; see Section 8 [TS 23.032][Mathew_Meins]
279 array Coordinate Reference System Wrapper [Fast and Readable Geographical Hashing (CTA-5009-A)][Consumer_Technology_Association]
280 string or array Symbol [https://github.com/mishoo/cbor.lisp/blob/e1428a5/clext-spec.txt][Mihai_Bazon]
281 array Linked list [https://github.com/mishoo/cbor.lisp/blob/e1428a5/clext-spec.txt][Mihai_Bazon]
282 unsigned integer Character [https://github.com/mishoo/cbor.lisp/blob/e1428a5/clext-spec.txt][Mihai_Bazon]
283 array Object [https://github.com/mishoo/cbor.lisp/blob/e1428a5/clext-spec.txt][Mihai_Bazon]
284 text string or byte string JSON Numeric Value, Represented as its JSON Text [https://gist.github.com/theory/ef667af1c725240e6e30d525786d58e6][David_Wheeler]
285 array SUIT_Report_Protected [RFC-ietf-suit-report-19]
286 array SUIT_Reference [RFC-ietf-suit-report-19]
287 map SUIT_Capability_Report [RFC-ietf-suit-report-19]
288-295 Unassigned
296 any isolate shared values within this scope [https://cbor.is4.site/sharedref-namespace][IS4]
297-300 Unassigned
301 text string or array Geohash String [Fast and Readable Geographical Hashing (CTA-5009-A)][Consumer_Technology_Association]
302-499 Unassigned
500 any Earmarked for CoRIM [draft-ietf-rats-corim-07]
501 map A CBOR tag that contains a corim-map. [TCG DICE Endorsement Architecture for Devices][TCG Errata for DICE Endorsement Architecture for Devices Version 1.1][TCG]
502-504 any Earmarked for CoRIM [draft-ietf-rats-corim-07]
505 bytes A CBOR tag that contains a conciseswid-tag-map. [TCG DICE Endorsement Architecture for Devices][TCG Errata for DICE Endorsement Architecture for Devices Version 1.1][TCG]
506 bytes A CBOR tag that contains a concisemid-tag-map. [TCG DICE Endorsement Architecture for Devices][TCG Errata for DICE Endorsement Architecture for Devices Version 1.1][TCG]
507-525 any Earmarked for CoRIM [draft-ietf-rats-corim-07]
526 map A CBOR tag that contains an xcorim-map. [TCG DICE Endorsement Architecture for Devices][TCG Errata for DICE Endorsement Architecture for Devices Version 1.1][TCG]
527 tagged signature block A CBOR tag that contains either: xcorimmap, or signed-xcorim. [TCG DICE Endorsement Architecture for Devices][TCG Errata for DICE Endorsement Architecture for Devices Version 1.1][TCG]
528-549 any Earmarked for CoRIM [draft-ietf-rats-corim-07]
550 bytes A CBOR tag that contains a UEID between 7 and 33 bytes. [TCG DICE Endorsement Architecture for Devices][TCG Errata for DICE Endorsement Architecture for Devices Version 1.1][TCG]
551 any Earmarked for CoRIM [draft-ietf-rats-corim-07]
552 unsigned integer A CBOR tag that contains a security version number that is evaluated with equivalence semantics. [TCG DICE Endorsement Architecture for Devices][TCG Errata for DICE Endorsement Architecture for Devices Version 1.1][TCG]
553 unsigned integer A CBOR tag that contains min-svn that identifies a security version number that is evaluated with greater than or equals semantics [TCG DICE Endorsement Architecture for Devices][TCG Errata for DICE Endorsement Architecture for Devices Version 1.1][TCG]
554 string A CBOR tag that contains a PEM encoded SubjectPublicKeyInfo. See Section 13 of [RFC 7468]. [TCG DICE Endorsement Architecture for Devices][TCG Errata for DICE Endorsement Architecture for Devices Version 1.1][TCG]
555 string A CBOR tag that contains a PEM encoded SubjectPublicKeyInfo. See Section 13 of [RFC 7468]. [TCG DICE Endorsement Architecture for Devices][TCG Errata for DICE Endorsement Architecture for Devices Version 1.1][TCG]
556 string A CBOR tag that contains an X.509 certificate chain created by the concatenation of as many PEM encoded X.509 certificates as needed. The certificates MUST be concatenated in order that each directly certifies the one preceding. [TCG DICE Endorsement Architecture for Devices][TCG Errata for DICE Endorsement Architecture for Devices Version 1.1][TCG]
557-559 any Earmarked for CoRIM [draft-ietf-rats-corim-07]
560 bytes A CBOR tag that contains a byte string interpreted as an array of bits. [TCG DICE Endorsement Architecture for Devices][TCG Errata for DICE Endorsement Architecture for Devices Version 1.1][TCG]
561-569 any Earmarked for CoRIM [draft-ietf-rats-corim-07]
570 map (spdm-toc-map, see CDDL) spdm-toc-map [TCG DICE Concise Evidence Binding for SPDM][TCG]
571 map (concise-evidence-map, see CDDL) concise-evidence-map [TCG DICE Concise Evidence Binding for SPDM][TCG]
572-599 any Earmarked for CoRIM [draft-ietf-rats-corim-07]
600 Unassigned
601 map (Claims-Set as per Appendix A of [RFC 9781]) Unprotected CWT Claims Set [RFC 9781] [RFC 9781]
602 array Detached EAT Bundle [RFC9711, Section 5]
603-1000 Unassigned
1001 map extended time [RFC9581, Section 3]
1002 map duration [RFC9581, Section 4]
1003 array period [RFC9581, Section 5]
1004 UTF-8 text string [RFC 3339] full-date string [RFC 8943]
1005-1009 Unassigned
1010 array: [id: text string, obj: any] Object type identifier [draft-rundgren-cotx-04]
1011-1039 Unassigned
1040 array of two arrays [1] Multi-dimensional Array, column-major order [RFC 8746]
1041-1047 Unassigned
1048 byte string IEEE OUI/CID [RFC 9542]
1049-1069 Unassigned
1070 map SUIT_Manifest as defined in Appendix A of [RFC-ietf-suit-manifest-34] [RFC-ietf-suit-manifest-34]
1071-1279 Unassigned
1280-1400 any alternatives 7..127, 1+2 encoding; see Section 9.1 [draft-bormann-cbor-notable-tags-07]
1401-18299 Unassigned
18300-18555 byte string Bare Hash value (COSE algorithm -256 to -1) [draft-bormann-cbor-notable-tags-09, Section 3.1.1]
18556 array [COSE algorithm identifier, Base Hash value] [draft-bormann-cbor-notable-tags-09, Section 3.1.1]
18557-18811 byte string Bare Hash value (COSE algorithm 1 to 255) [draft-bormann-cbor-notable-tags-09, Section 3.1.1]
18812-20852 Unassigned
20853 any description of the value instead of the value itself [https://cbor.is4.site/quoted][IS4]
20854-21064 Unassigned
21065 text string I-Regexp [draft-bormann-cbor-notable-tags-11, Section 2.1][RFC 9485]
21066 Array[UTF8string, UTF8string?] ECMAScript RegExp [https://262.ecma-international.org/14.0/#sec-regexp-regular-expression-objects] [https://github.com/hildjj/cbor-specs/blob/main/regexp.md][Joe_Hildebrand]
21067-21333 Unassigned
21334 uint (always invalid in interchange) programming aid for simple values [draft-bormann-cbor-notable-tags-12, Section 10.2 ]
21335-21606 Unassigned
21607 unsigned integer a CBOR Tag identifier [https://cbor.is4.site/cbor-tag][IS4]
21608-22097 Unassigned
22098 multiple hint that indicates an additional level of indirection [http://cbor.schmorp.de/indirection][Marc_A._Lehmann]
22099-25440 Unassigned
25441 Array containing at most one array followed by at most one map Capture [3] [https://github.com/japhb/cbor-specs/blob/main/capture.md][Geoffrey_Broadwell]
25442-32767 Unassigned
32768 unsigned integer Identifier for a FHIR constant [Stefan_Genchev] template/32768
32769 multiple External reference [https://gitlab.com/Hawk777/cbor-specs/-/blob/main/external-reference.md][Christopher_Head]
32770-32869 unsigned integer Used to mark pointers in PSA Crypto API IPC implementation [Ole_Saether] template/32770-32869
32870 multiple Logical operator: NONE / NOT. Encodes the logical operation (!item1&&!item2&&!item3&&..., if array), otherwise (!item). [Jon_Caruana] template/32870
32871 array Logical operator: ANY. Encodes the logical operation (item1||item2||item3||...). [Jon_Caruana] template/32871
32872 array Logical operator: ALL. Encodes the logical operation (item1&&item2&&item3&&...). [Jon_Caruana] template/32872
32873-39999 Unassigned
40000 unsigned integer ur:known-value, Semantic signifier [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40001 byte string ur:digest, 32-byte SHA-256 digest [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40002 array ur:encrypted, IETF ChaCha20-Poly1305 ([RFC 8439]) encrypted message [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40003 array ur:compressed, [RFC 1951] DEFLATE-compressed message [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40004 multiple ur:request, Transaction Request identifier [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40005 multiple ur:response, Transaction response identifier [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40006 unsigned integer or text string ur:function, Envelope expression function identifier [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40007 unsigned integer or text string ur:parameter, Envelope expression parameter identifier [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40008 unsigned integer or text string ur:placeholder, Envelope expression placeholder identifier [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40009 unsigned integer or text string ur:replacement, Envelope expression replacement identifier [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40010 byte string ur:agreement-private-key, Curve25519 private key for X25519 key agreement [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40011 byte string ur:agreement-public-key, Curve25519 public key for X25519 key agreement [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40012 byte string ur:arid, Apparently Random Identifier [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40013 array ur:crypto-prvkeys, Private keys for cryptographic operations [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40014 byte string ur:nonce, Cryptographic nonce [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40015 array ur:password, Scrypt-hashed password [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40016 byte string ur:crypto-prvkeys, Private key base (key material) [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40017 array ur:crypto-pubkeys, Public key base (signing and agreement public key bundle) [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40018 byte string ur:salt, Random salt used for hash tree decorrelation [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40019 array ur:crypto-sealed, Encrypted message and ephemeral public key [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40020 multiple ur:signature, Cryptographic signature [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40021 byte string ur:signing-private-key, Cryptographic private key used for signing [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40022 multiple ur:signing-public-key, Cryptographic public key used for signing [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40023 byte string ur:crypto-key, Cryptographic key used for symmetric encryption [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40024 multiple ur:xid, Extensible identifier or XID Document [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40025 byte string ur:reference, Cryptographically secure reference to an object [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40026 unsigned integer or text string ur:event, Event identifier [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40027 tagged array ur:encrypted-key, Content key encrypted with a derivation function [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40028-40099 Unassigned
40100 array ur:mlkem-private-key, Private key for MLKEM key encapsulation [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40101 array ur:mlkem-public-key, Public key for MLKEM key encapsulation [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40102 array ur:mlkem-ciphertext, Ciphertext for MLKEM key encapsulation [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40103 array ur:mldsa-private-key, Private key for MLDSA signature generation [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40104 array ur:mldsa-public-key, Public key for MLDSA signature verification [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40105 array ur:mldsa-signature, MLDSA signature [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40106-40299 Unassigned
40300 map ur:seed, Cryptographic seed [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40301-40302 Unassigned
40303 map ur:hdkey, Bitcoin BIP-32 HD key [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40304 map ur:keypath, Bitcoin BIP-32 key derivation path [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40305 map ur:coin-info, Cryptographic asset and network specifier [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40306 map ur:eckey, Bitcoin elliptic curve key (private or public) [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40307 map ur:address, Cryptocurrency address [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40308 map ur:output-descriptor, Bitcoin output descriptor [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40309 byte string ur:sskr, Sharded Secret Key Reconstruction (SSKR) share [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40310 byte string ur:psbt, Partially Signed Bitcoin Transaction [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40311 map ur:account-descriptor, Bitcoin account descriptor [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40312-40799 Unassigned
40800 text string ur:ssh-private, Text format SSH private key [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40801 text string ur:ssh-public, Text format SSH public key [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40802 text string ur:ssh-signature, Text format SSH signature [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40803 text string ur:ssh-certificate, Text format SSH certificate [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
40804-40918 Unassigned
40919 multiple (uint or array [uint, uint]) Concordium smart contract address [https://proposals.concordium.com/CIS/cis-7.html#smart-contract-address][Thomas_Dinsdale-Young] template/40919
40920-41727 Unassigned
41728 array, unsigned integer or unsigned bignum Fraction [https://medyro.eu/specification/IANA/CBOR%20Tags/Fraction/][Medyro] template/41728
41729 array, unsigned integer or unsigned bignum Fraction (-NaN signals) [https://medyro.eu/specification/IANA/CBOR%20Tags/Fraction/][Medyro] template/41729
41730 array, unsigned integer or unsigned bignum Fraction (+NaN signals) [https://medyro.eu/specification/IANA/CBOR%20Tags/Fraction/][Medyro] template/41730
41731 array, unsigned integer or unsigned bignum Fraction (Both NaNs signal) [https://medyro.eu/specification/IANA/CBOR%20Tags/Fraction/][Medyro] template/41731
41732-42599 Unassigned
42600 map A confidentiality clearance. The key value pairs of the map are defined in ADatP-4774.8 [Aidan_Murdock] template/42600
42601 array A metadata binding. The elements of the array are defined in AdatP-4778.8. The tag is also used as part of the magic number in on-disk detached and encapsulating bindings. [Aidan_Murdock] template/42601
42602 map A collection of NCMS metadata elements. The key value pairs of the map are defined in AdatP-5636.8 [Aidan_Murdock] template/42602
42603-42999 Unassigned
43000 array Single complex number: array elements are real (I) and imaginary (Q) components [Saajan_Chana] template/43000
43001 array Array of complex numbers in interleaved form: complex value k is stored with real (I) part at array index 2k and imaginary (Q) part at index (2k + 1) [Saajan_Chana] template/43001
43002-44251 Unassigned
44252 array Metrological value (quantity value with unit of measure, SI prefix and GUM measurement uncertainty) [https://github.com/OpenChargingTechnology/Whitepapers/blob/master/MetrologicalCBOR/README.md][Achim_Friedland] template/44252
44253-46009 Unassigned
46010 byte string, exactly 4 bytes CRC-32/ISO-HDLC digest [Hans_Larsen] template/46010
46011 byte string, exactly 16 bytes MD5 digest [Hans_Larsen] template/46011
46012-49999 Unassigned
50000 integer PlatformV_IS_ID [https://github.com/arthurwangtz/platformv-cbor][Wang_Tongzhou]
50001 text string PlatformV_IS_NAME [https://github.com/arthurwangtz/platformv-cbor][Wang_Tongzhou]
50002 any PlatformV_IS_VALUE [https://github.com/arthurwangtz/platformv-cbor][Wang_Tongzhou]
50003 array PlatformV_HAS_COMPOSITE_VALUE [https://github.com/arthurwangtz/platformv-cbor][Wang_Tongzhou]
50004 array PlatformV_HAS_MAPPED_VALUE [https://github.com/arthurwangtz/platformv-cbor][Wang_Tongzhou]
50005 array PlatformV_HAS_OBJ_ID [https://github.com/arthurwangtz/platformv-cbor][Wang_Tongzhou]
50006 array PlatformV_HAS_OBJ_TAG [https://github.com/arthurwangtz/platformv-cbor][Wang_Tongzhou]
50007 array PlatformV_HAS_CHILD [https://github.com/arthurwangtz/platformv-cbor][Wang_Tongzhou]
50008 array PlatformV_HAS_PROPERTY [https://github.com/arthurwangtz/platformv-cbor][Wang_Tongzhou]
50009 array PlatformV_HAS_META [https://github.com/arthurwangtz/platformv-cbor][Wang_Tongzhou]
50010 array PlatformV_HAS_EVENT [https://github.com/arthurwangtz/platformv-cbor][Wang_Tongzhou]
50011 array PlatformV_HAS_ACTION [https://github.com/arthurwangtz/platformv-cbor][Wang_Tongzhou]
50012 integer PlatformV_IS_TYPE [https://github.com/arthurwangtz/platformv-cbor][Wang_Tongzhou]
50013-51996 Unassigned
51997 array A tag value of 51997 indicates that the payload is CBOR-LD. [https://json-ld.github.io/cbor-ld-spec/#cbor-tags-for-cbor-ld][Wesley_Smith] template/51997
51998-55798 Unassigned
55799 (any) Self-described CBOR; see Section 3.4.6 [RFC 8949]
55800 tagged byte string indicates that the file contains CBOR Sequences [RFC 9277]
55801 tagged byte string indicates that the file starts with a CBOR-Labeled Non-CBOR Data label. [RFC 9277]
55802-56499 Unassigned
56500 array (major type 4) Compressed byte string [https://github.com/dectris/documentation/blob/main/cbor/dectris-compression-tag.md][Dirk_Boye]
56501-57341 Unassigned
57342 array Identify and define a set of record structures (each a sequence of property names) that can be referenced as tags in the included value (and the scope for the record tag definitions) [https://github.com/kriszyp/cbor-records][Kris_Zyp]
57343 array Identify and define a record structure (a sequence of property names), and use that record structure definition to interpret the included values. [https://github.com/kriszyp/cbor-records][Kris_Zyp]
57344-57599 array References a defined record structure, using that referenced record definition to interpret the included values. [https://github.com/kriszyp/cbor-records][Kris_Zyp]
57600-59999 Unassigned
60000 array The tagged CBOR array contains attestation evidence data with an Intel TEE quote. [Shanwei_Cen] template/60000
60001 array The tagged CBOR array contains attestation evidence data with an Intel TEE report. [Shanwei_Cen] template/60001
60002 array The tagged CBOR array contains attestation evidence data with an Intel SGX report. [Shanwei_Cen] template/60002
60003-60009 Unassigned
60010 array The tagged CBOR array containing a numeric expression. [https://github.com/nedmsmith/draft-cds-rats-intel-corim-profile/blob/main/draft-cds-rats-intel-corim-profile.md][Ned_Smith]
60011-60019 Unassigned
60020 array The tagged CBOR array containing a set of digests expression. [https://github.com/nedmsmith/draft-cds-rats-intel-corim-profile/blob/main/draft-cds-rats-intel-corim-profile.md][Ned_Smith]
60021 array The tagged CBOR array containing a set of strings expression. [https://github.com/nedmsmith/draft-cds-rats-intel-corim-profile/blob/main/draft-cds-rats-intel-corim-profile.md][Ned_Smith]
60022-65534 Unassigned
65535 (none valid) always invalid; see Section 10.1 [draft-bormann-cbor-notable-tags-02]
65536-79999 Unassigned
80000-80099 byte string, array or map Private tags as suggested in [https://mailarchive.ietf.org/arch/msg/cbor/NJlskB63pjXFt5a6S37tiwJBbCM]. [Tony_Putman] template/80000-80099
80100-80149 byte string, array or map Private tags as suggested in [https://mailarchive.ietf.org/arch/msg/cbor/NJlskB63pjXFt5a6S37tiwJBbCM/]. [Unchained_Infra_Ops] template/80100-80149
80150-80199 byte string, array or map Private tags as suggested in [https://mailarchive.ietf.org/arch/msg/cbor/NJlskB63pjXFt5a6S37tiwJBbCM/]. [Janis_Danisevskis] template/80150-80199
80200-133132 Unassigned
133133 array ZeWIF (Zcash Wallet Interchange Format) document; the tag encloses a two-element array [version, payload] whose payload is a CBOR map conforming to the version's ZeWIF schema. In a stored document this tag is enclosed in tag 55799 (Self-Described CBOR). [Kris_Nuttycombe][ZeWIF: Zcash Wallet Interchange Format] template/133133
133134-14245119 Unassigned
14245120-14245220 array or map A tag within this range will indicate that a CBOR-encoded payload contains a W3C verifiable credential, data integrity proof value. The additional specificity of the tag in this range is use to identify a particular cryptographic suite, cryptographic feature, or proof role (base or derived). [Greg_Bernstein] template/14245120-14245220
14245221-15309735 Unassigned
15309736 map (major type 5) RAINS Message [https://britram.github.io/rains-prototype][Brian_Trammell]
15309737-827539797 Unassigned
827539798 array Universal Saves Format bundle [Hans_Larsen] template/827539798
827539799-1146111422 Unassigned
1146111423 map TCG DICE Protection Environment profile descriptor [TCG DICE Protection Environment][TCG] template/1146111423
1146111424-1298360422 Unassigned
1298360423 map MoaT change-of-status marker [https://github.com/M-o-a-T/moat/blob/main/doc/common/cbor.rst][Matthias_Urlichs]
1298360424-1298493253 Unassigned
1298493254 map MoaT end-of-file marker [https://github.com/M-o-a-T/moat-util/][Matthias_Urlichs]
1298493255-1299145043 Unassigned
1299145044 array MoaT file identifier / details [https://github.com/M-o-a-T/moat-util/][Matthias_Urlichs]
1299145045-1330664269 Unassigned
1330664270 byte-string A CBOR encoded Openswan configuration file, as stored on disk for unit test cases. [Michael_Richardson][Samir_Hussain] template/1330664270
1330664271-1347571279 Unassigned
1347571280 Proof of Process Packet (PPPP) A cryptographically anchored data structure used for digital authorship attestation, capturing the authorship process through entangled Verifiable Delay Functions (VDFs) and behavioral biometrics. [witnessd Proof of Process Evidence Format, Version 1.3.0][David_Lee_Condrey] template/1347571280
1347571281 Compact Evidence Reference A cryptographic pointer to a full Proof of Process Evidence Packet, used for embedding authorship claims in space-constrained contexts (e.g., metadata, QR codes). [witnessd Proof of Process Evidence Format, Version 1.3.0][David_Lee_Condrey] template/1347571281
1347571282-1347571541 Unassigned
1347571542 array ur:provenance, Provenance Mark [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-006-urtypes.md][Wolf_McNally]
1347571543-1398229315 Unassigned
1398229316 map Concise Software Identifier (CoSWID) [RFC 9393]
1398229317-1413829459 Unassigned
1413829460 any Explicitly none. [draft-bormann-cbor-notable-tags-15, Section 10.3][Joe_Hildebrand] template/1413829460
1413829461-1463894559 Unassigned
1463894560 Writers Authenticity Report (WAR) An Attestation Result structure produced by Verifiers appraising Proof of Process Evidence, conveying verification verdicts, confidence scores, and forensic assessments per the IETF RATS architecture. [witnessd Proof of Process Evidence Format, Version 1.3.0][David_Lee_Condrey] template/1463894560
1463894561-1482048303 Unassigned
1482048304-1482048346 integer or map Xbox Virtual Container identifiers for use with [RFC 9277] [Jon_Caruana] template/1482048304-1482048346
1482048347-1668546816 Unassigned
1668546817-1668612095 byte string or any CBOR data item (see Appendix B of [RFC 9277]) the representation of content-format ct < 65025 is indicated by tag number TN(ct) = 0x63740101 + (ct / 255) * 256 + ct % 255 [RFC 9277]
1668612096-1701996914 Unassigned
1701996915 array Array of content-addressed blocks and ERIS read capabilities [Endo_Renberg] template/1701996915
1701996916 array ERIS-FS image header [Endo_Renberg] template/1701996916
1701996917-1735551331 Unassigned
1735551332 array PromiseGrid message envelope [Steve_Traugott] template/1735551332
1735551333-4294967294 Unassigned
4294967295 (none valid) always invalid; see Section 10.1 [draft-bormann-cbor-notable-tags-02]
4294967296 map Intel FPGA SPDM Manifest [Andrew_Draper] template/4294967296
4294967297-18446744073709551614 Unassigned
18446744073709551615 (none valid) always invalid; Section 10.1 [draft-bormann-cbor-notable-tags-02]

Timescales

Registration Procedure(s)
RFC and Expert Review Required
Expert(s)
Henk Birkholz, Esko Dijk
Reference
[RFC 9581]
Available Formats

CSV
Timescale Value Semantics Reference
UTC 0 UTC with POSIX Epoch [RFC 9581]
TAI 1 TAI with PTP Epoch [RFC 9581]
Unassigned 2-18446744073709551615

Time Tag Map Keys

Registration Procedure(s)
Specification Required
Expert(s)
Henk Birkholz, Esko Dijk
Reference
[RFC 9581]
Available Formats

CSV
Value Semantics Reference
-18446744073709551616..-19 Unassigned
-18 attoseconds [RFC 9581]
-17..-16 Unassigned
-15 femtoseconds [RFC 9581]
-14 Unassigned
-13 timescale (elective) [RFC 9581]
-12 picoseconds [RFC 9581]
-11 IXDTF Suffix Information (elective) [RFC 9581][RFC 9557]
-10 IXDTF Time Zone Hint (elective) [RFC 9581][RFC 9557]
-9 nanoseconds [RFC 9581]
-8 Guarantee [RFC 9581]
-7 Uncertainty [RFC 9581]
-6 microseconds [RFC 9581]
-5 Offset-Scaled Log Variance [RFC 9581]
-4 Clock Accuracy [RFC 9581]
-3 milliseconds [RFC 9581]
-2 Clock Class [RFC 9581]
-1 timescale (elective) legacy [RFC 9581]
0 Unassigned
1 base time value as in CBOR Tag 1 [RFC 8949][RFC 9581]
2-3 Unassigned
4 base time value as in CBOR Tag 4 [RFC 8949][RFC 9581]
5 base time value as in CBOR Tag 5 [RFC 8949][RFC 9581]
6-9 Unassigned
10 IXDTF Time Zone Hint (critical) [RFC 9581][RFC 9557]
11 IXDTF Suffix Information (critical) [RFC 9581][RFC 9557]
12 Unassigned
13 timescale (critical) [RFC 9581]
14-18446744073709551615 Unassigned

Contact Information

ID Name Contact URI Last Updated
[Achim_Friedland] Achim Friedland mailto:achim.friedland&graphdefined.com 2026-08-19
[Aidan_Murdock] Aidan Murdock mailto:aidan.murdock&ncia.nato.int 2022-05-24
[Alfredo_Di_Napoli] Alfredo Di Napoli mailto:alfredo.dinapoli&iohk.io 2017-08-25
[Andrew_Draper] Andrew Draper mailto:andrew.draper&intel.com 2021-12-10
[Brian_Trammell] Brian Trammell mailto:ietf&trammell.ch 2016-08-17
[Christopher_Head] Christopher Head mailto:chead&chead.ca 2022-12-28
[Consumer_Technology_Association] Consumer Technology Association mailto:standards&cta.tech 2024-06-11
[Danilo_Vidovic] Danilo Vidovic mailto:cbor&allthingstalk.com 2018-04-17
[David_Lee_Condrey] David Lee Condrey mailto:david&writerslogic.com 2026-02-06
[David_Wheeler] David_Wheeler mailto:david&justatheory.com 2025-05-16
[Dirk_Boye] Dirk Boye mailto:dirk.boye&dectris.com 2024-02-12
[Emile_Cormier] Emile Cormier mailto:emile.cormier.jr&gmail.com 2020-03-30
[Endo_Renberg] Endo Renberg mailto:pukkamustard&posteo.net 2023-07-31
[Geoffrey_Broadwell] Geoffrey Broadwell mailto:gjb&sonic.net 2021-11-09
[Greg_Bernstein] Greg Bernstein mailto:gregb&grotto-networking.com 2024-08-28
[Hans_Larsen] Hans Larsen mailto:spec&1retro.com 2026-09-18
[IS4] IS4 mailto:is4.site&gmail.com 2025-03-06
[Janis_Danisevskis] Janis Danisevskis mailto:jdanisevskis&aurora.tech 2025-09-04
[Joe_Hildebrand] Joe Hildebrand mailto:joe-ietf&cursive.net 2026-02-11
[Jon_Caruana] Jon Caruana mailto:joncar&xbox.com 2025-09-08
[Kris_Nuttycombe] Kris Nuttycombe mailto:kris&zodl.com 2026-07-20
[Kris_Zyp] Kris Zyp mailto:kriszyp&gmail.com 2022-05-23
[Lucas_Clemente] Lucas Clemente mailto:lucas&clemente.io 2014-07-01
[Marc_A._Lehmann] Marc A. Lehmann mailto:cbor&schmorp.de 2013-11-26
[Mathew_Meins] Mathew Meins mailto:mm&blackhelicopters.net 2021-02-01
[Matthias_Urlichs] Matthias Urlichs mailto:matthias&urlichs.de 2025-02-13
[Medyro] Medyro mailto:Curious.Charr&web.de 2026-04-02
[Michael_B._Jones] Michael B. Jones mailto:mbj&microsoft.com 2018-05-04
[Michael_Richardson] Michael Richardson mailto:mcr&xelerance.com 2021-01-25
[Mihai_Bazon] Mihai Bazon mailto:mihai.bazon&gmail.com 2025-04-03
[Ned_Smith] Ned Smith mailto:ned.smith&intel.com 2025-05-12
[Ole_Saether] Ole Saether mailto:ole.saether&nordicsemi.no 2024-06-28
[Peter_Occil] Peter Occil mailto:poccil14&gmail.com 2018-11-09
[Ravi_Raju] Ravi Raju mailto:ravir&employees.org 2018-03-06
[Saajan_Chana] Saajan Chana mailto:saajan.chana&cambridgeconsultants.com 2022-07-20
[Sami_Vaarala] Sami Vaarala mailto:sami.vaarala&iki.fi 2020-03-18
[Samir_Hussain] Samir Hussain mailto:shussain&xelerance.com 2021-01-25
[Shane_Holloway] Shane Holloway mailto:shane.holloway&ieee.org 2018-10-25
[Shanwei_Cen] Shanwei Cen mailto:shanwei.cen&intel.com 2023-01-12
[Stefan_Genchev] Stefan Genchev mailto:stefan.genchev&tum.de 2022-12-09
[Steve_Traugott] Steve Traugott mailto:ietf-poc&t7a.org 2026-07-20
[TCG] Trusted Computing Group mailto:iana-requests&trustedcomputinggroup.org 2024-03-20
[Thomas_Dinsdale-Young] Thomas Dinsdale-Young mailto:ty&concordium.com 2025-08-18
[Tony_Putman] Tony Putman mailto:anthony.putman&dyson.com 2023-04-26
[Unchained_Infra_Ops] Infra Ops mailto:cbor&unchained.com 2025-09-29
[Volker_Mische] Volker Mische mailto:volker.mische&gmail.com 2024-03-05
[Wang_Tongzhou] Wang Tongzhou mailto:tongzhou.wang&siemens.com 2022-10-20
[Wesley_Smith] Wesley Smith mailto:wsmith&digitalbazaar.com 2025-05-05
[Wolf_McNally] Wolf McNally mailto:wolf&wolfmcnally.com 2025-04-28

Footnote

[1] 
second element of outer array in data item is native CBOR array 
(major type 4) or Typed Array (one of Tag 64..87)