CBOR Diagnostic Notation: "cri" Application-oriented Extension
draft-bormann-core-cri-diagnostic-notation-00
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Author | Carsten Bormann | ||
| Last updated | 2026-11-02 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
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draft-bormann-core-cri-diagnostic-notation-00
Constrained RESTful Environments C. Bormann
Internet-Draft Universität Bremen TZI
Intended status: Standards Track 2 November 2026
Expires: 6 May 2027
CBOR Diagnostic Notation: "cri" Application-oriented Extension
draft-bormann-core-cri-diagnostic-notation-00
Abstract
For the Concise Binary Object Representation (CBOR), a Concise
Diagnostic Notation (CDN) has been defined in draft-ietf-cbor-edn-
literals. This provides an extension point for "App-Extension
Identifiers" registry in the "Concise Diagnostic Notation" registry
group, supporting text representations of CBOR tags and other
structures to enhance usability.
The present document specifies an app-extension and registers an app-
extension identifier for CBOR tag 99, Constrained Resource
Identifiers (CRI), as defined in RFC-to-be 9988.
// (This cref will be removed by the RFC editor:) This document
// carries the specification of the cri'' application- oriented
// prefix for CBOR diagnostic notation. This specification used to
// be in the CoRE WG document for CRIs, became part of the CBOR WG
// document for CBOR diagnostic notation when the CBOR WG document
// was delayed, and was then deleted from that document as it is
// outside the scope of the CBOR WG. So this document now goes back
// to the CoRE WG, as a "new" individual submission.
About This Document
This note is to be removed before publishing as an RFC.
Status information for this document may be found at
https://datatracker.ietf.org/doc/draft-bormann-core-cri-diagnostic-
notation/.
Discussion of this document takes place on the core Working Group
mailing list (mailto:core@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/core/. Subscribe at
https://www.ietf.org/mailman/listinfo/core/.
Source for this draft and an issue tracker can be found at
https://github.com/cabo/draft-bormann-core-cri-diagnostic-notation.
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Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 6 May 2027.
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions and Definitions . . . . . . . . . . . . . . . 3
2. Concise Resource Identifiers: The "cri" Extension . . . . . . 3
2.1. cri: ABNF Definition of URI Representation of a CRI . . . 3
3. Security Considerations . . . . . . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
4.1. Concise Diagnostic Notation App-extension Identifiers
Registry . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Normative References . . . . . . . . . . . . . . . . . . . . 6
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
(To be derived from abstract, q.v.) [STD94]
1.1. Conventions and Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[BCP14] (RFC2119) (RFC8174) when, and only when, they appear in all
capitals, as shown here.
2. Concise Resource Identifiers: The "cri" Extension
The app-extension identifier "cri" is used to notate a CDN literal
for a CRI reference as defined in [I-D.ietf-core-href].
The input of the literal is a URI Reference as per [RFC3986] or an
IRI Reference as per [RFC3987].
The value of the literal is a CRI reference that can be converted to
the text of the literal using the procedure of Section 6.1 of
[I-D.ietf-core-href]. Note that there may be more than one CRI
reference that can be converted to the URI/IRI reference given;
implementations are expected to favor the simplest variant available
and make non-surprising choices otherwise. In the all-uppercase
variant of the app-prefix, the value is enclosed in a tag number 99.
As an example, the CDN
cri'https://example.com/bottarga/shaved'
CRI'https://example.com/bottarga/shaved'
is equivalent to
[-4, ["example", "com"], ["bottarga", "shaved"]]
99([-4, ["example", "com"], ["bottarga", "shaved"]])
See Section 2.1 for an ABNF [STD68] definition for the content of cri
literals.
2.1. cri: ABNF Definition of URI Representation of a CRI
It can be expected that implementations of the app-extension
identifier "cri" will make use of platform-provided URI
implementations, which will include a URI parser.
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In case such a URI parser is not available or inconvenient to
integrate, a grammar of the content of cri literals is provided by
the ABNF for URI-reference in Section 4.1 of RFC 3986 [RFC3986] with
certain re-arrangements taken from Section 5.2.4 of
[I-D.ietf-cbor-edn-literals]; these are reproduced in Figure 1. If
the content is not ASCII only (i.e., for IRIs), first apply
Section 3.1 of [RFC3987] and apply this grammar to the result.
app-string-cri = URI-reference
; ABNF from RFC 3986:
URI = scheme ":" hier-part [ "?" query ] [ "#" fragment ]
hier-part = "//" authority path-abempty
/ path-absolute
/ path-rootless
/ path-empty
URI-reference = URI / relative-ref
absolute-URI = scheme ":" hier-part [ "?" query ]
relative-ref = relative-part [ "?" query ] [ "#" fragment ]
relative-part = "//" authority path-abempty
/ path-absolute
/ path-noscheme
/ path-empty
scheme = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
authority = [ userinfo "@" ] host [ ":" port ]
userinfo = *( unreserved / pct-encoded / sub-delims / ":" )
host = IP-literal / IPv4address / reg-name
port = *DIGIT
IP-literal = "[" ( IPv6address / IPvFuture ) "]"
IPvFuture = "v" 1*HEXDIG "." 1*( unreserved / sub-delims / ":" )
; Use IPv6address, h16, ls32, IPv4adress, dec-octet as re-arranged
; for PEG Compatibility in Figure 6 of [RFC XXXX]:
IPv6address = 6( h16 ":" ) ls32
/ "::" 5( h16 ":" ) ls32
/ [ h16 ] "::" 4( h16 ":" ) ls32
/ [ h16 *1( ":" h16 ) ] "::" 3( h16 ":" ) ls32
/ [ h16 *2( ":" h16 ) ] "::" 2( h16 ":" ) ls32
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/ [ h16 *3( ":" h16 ) ] "::" h16 ":" ls32
/ [ h16 *4( ":" h16 ) ] "::" ls32
/ [ h16 *5( ":" h16 ) ] "::" h16
/ [ h16 *6( ":" h16 ) ] "::"
h16 = 1*4HEXDIG
ls32 = ( h16 ":" h16 ) / IPv4address
IPv4address = dec-octet "." dec-octet "." dec-octet "." dec-octet
dec-octet = "25" %x30-35 ; 250-255
/ "2" %x30-34 DIGIT ; 200-249
/ "1" 2DIGIT ; 100-199
/ %x31-39 DIGIT ; 10-99
/ DIGIT ; 0-9
reg-name = *( unreserved / pct-encoded / sub-delims )
path = path-abempty ; begins with "/" or is empty
/ path-absolute ; begins with "/" but not "//"
/ path-noscheme ; begins with a non-colon segment
/ path-rootless ; begins with a segment
/ path-empty ; zero characters
path-abempty = *( "/" segment )
path-absolute = "/" [ segment-nz *( "/" segment ) ]
path-noscheme = segment-nz-nc *( "/" segment )
path-rootless = segment-nz *( "/" segment )
path-empty = 0<pchar>
segment = *pchar
segment-nz = 1*pchar
segment-nz-nc = 1*( unreserved / pct-encoded / sub-delims / "@" )
; non-zero-length segment without any colon ":"
pchar = unreserved / pct-encoded / sub-delims / ":" / "@"
query = *( pchar / "/" / "?" )
fragment = *( pchar / "/" / "?" )
pct-encoded = "%" HEXDIG HEXDIG
unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"
reserved = gen-delims / sub-delims
gen-delims = ":" / "/" / "?" / "#" / "[" / "]" / "@"
sub-delims = "!" / "$" / "&" / "'" / "(" / ")"
/ "*" / "+" / "," / ";" / "="
Figure 1: ABNF Definition of URI Representation of a CRI
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3. Security Considerations
TODO Security
4. IANA Considerations
// RFC Editor: please replace RFC-XXXX with the RFC number of this
// RFC, [IANA.concise-diagnostic-notation] with a reference to the
// new registry group, and remove this note.
4.1. Concise Diagnostic Notation App-extension Identifiers Registry
IANA is requested to register the "cri" app-extension identifier as
per Table 1 in the "App-Extension Identifiers" registry in the
"Concise Diagnostic Notation" registry group [IANA.concise-
diagnostic-notation], with the Change Controller "IETF".
+===============+=====================+======================+
| app-extension | Description | Reference |
| identifier | | |
+===============+=====================+======================+
| cri | Constrained | RFC-XXXX, |
| | Resource Identifier | [I-D.ietf-core-href] |
+---------------+---------------------+----------------------+
Table 1: app-extension Identifier "cri"
5. Normative References
[BCP14] Best Current Practice 14,
<https://www.rfc-editor.org/info/bcp14>.
At the time of writing, this BCP comprises the following:
Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[I-D.ietf-cbor-edn-literals]
Bormann, C., "Concise Diagnostic Notation (CDN)", Work in
Progress, Internet-Draft, draft-ietf-cbor-edn-literals-29,
31 October 2026, <https://datatracker.ietf.org/doc/html/
draft-ietf-cbor-edn-literals-29>.
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[I-D.ietf-core-href]
Bormann, C. and H. Birkholz, "Constrained Resource
Identifiers", Work in Progress, Internet-Draft, draft-
ietf-core-href-30, 21 November 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-core-
href-30>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/rfc/rfc3986>.
[RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource
Identifiers (IRIs)", RFC 3987, DOI 10.17487/RFC3987,
January 2005, <https://www.rfc-editor.org/rfc/rfc3987>.
[STD68] Internet Standard 68,
<https://www.rfc-editor.org/info/std68>.
At the time of writing, this STD comprises the following:
Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/info/rfc5234>.
[STD94] Internet Standard 94,
<https://www.rfc-editor.org/info/std94>.
At the time of writing, this STD comprises the following:
Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/info/rfc8949>.
Acknowledgments
TODO acknowledge.
Author's Address
Carsten Bormann
Universität Bremen TZI
Postfach 330440
D-28359 Bremen
Germany
Phone: +49-421-218-63921
Email: cabo@tzi.org
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