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URN Specification for the International Organization for Standardization (ISO)

Introduction

This document specifies the Uniform Resource Name (URN) namespace for identifiers published by the International Organization for Standardization (ISO). It is based on RFC 5141 (the original ISO URN namespace registration) with extensions implemented in the PubID gem, referred to here as RFC 5141-bis.

RFC 5141 assigned the namespace ID (NID) "iso" and defined the original syntax for identifying ISO documents, their editions, supplements, and extracted resources. This specification extends RFC 5141 to address the following gaps identified in practice:

  • Copublishers — RFC 5141 defines a fixed set of originators. This specification supports dynamic copublisher combinations (e.g., iso-iec-ieee, iso-astm).

  • Extended document types — Additional deliverable types beyond those in RFC 5141, including Directives (dir), Directive Supplements (dir-sup), and IWA Supplements (iwa-sup).

  • Typed stage abbreviations — RFC 5141 uses only harmonized stage codes (stage-XX.XX). This specification also supports short stage abbreviations (WD, CD, DIS, FDIS, PDAM, DAM, FDAM, DCOR, FDCOR, CDTS, DTS, FDTS, WDS).

  • Supplement chains — Nested supplements (e.g., a Corrigendum to an Amendment) with explicit ordering semantics.

  • Explicit language specification — Language codes are always emitted explicitly rather than relying on a default.

Namespace ID

iso

Registration Information

Version: RFC 5141-bis (based on RFC 5141 Version 2.1, 2007-12-13)

Declared Registrant of the Namespace

ISO Central Secretariat
International Organization for Standardization (ISO)
Case Postale 56
CH-1211 Geneva 20
Switzerland
E-mail: goodwin@iso.org

Declaration of Structure

Definition

The Namespace Specific Strings (NSSs) of all URNs assigned by ISO conform to the syntax defined in Section 2.2 of RFC 2141.

The NSS has the following ABNF specification:

NSS           = std-nss

std-nss       = "std:" docidentifier *supplement [addition]

docidentifier = originator [":" type] ":" docnumber [":" partnumber]
                [[":" status] ":" edition]
                [":" docversion] [":" language]

originator    = publisher *("-" copublisher)

publisher     = "iso" / "iec"

copublisher   = "iec" / "cie" / "astm" / "ieee" / "itu" / "sae"
                / other-org

other-org     = 1*(ALPHA / DIGIT)

type          = "data" / "guide" / "isp" / "iwa" /
                "pas" / "r" / "tr" / "ts" / "tta" /
                "dir" / "dir-sup" / "iwa-sup"

docnumber     = DIGITS

partnumber    = "-" 1*( DIGIT / ALPHA / "-" )

status        = ( "draft" / "cancelled" ) / stage

stage         = "stage-" stagecode ["." iteration]
              / stage-abbr ["." iteration]

stage-abbr    = "WD" / "WDS" / "CD" / "CDV" / "DIS" / "FDIS"
              / "PDAM" / "DAM" / "FDAM" / "DCOR" / "FDCOR"
              / "CDTS" / "DTS" / "FDTS" / "PRF"
              / "PWI" / "NP" / "AWI" / "NWIP"

stagecode     = DIGIT DIGIT "." DIGIT DIGIT

iteration     = "v" DIGITS

edition       = "ed-" DIGITS

docversion    = "v" (simpleversion / isoversion)

simpleversion = DIGITS

isoversion    = baseversion *includedsuppl

baseversion   = DIGITS

includedsuppl = "-" suppltype supplnumber ["." supplversion]

language      = lang-code *("," lang-code)

lang-code     = 1*2(ALPHA)

supplement    = ":" suppltype ":" supplnumber
                [":" supplversion] [":" language]

suppltype     = "amd" / "cor" / "sup" / "add"

supplnumber   = DIGITS

supplversion  = "v" DIGITS

addition      = techdefined / isodefined

techdefined   = ":tech" *techelement

techelement   = <unspecified>

isodefined    = <unspecified>

DIGITS        = DIGIT *DIGIT

DIGIT         = %x30-39 ; 0-9

ALPHA         = %x41-5A / %x61-7A ; A-Z / a-z

Element Descriptions

originator

The organization (or organizations) from which a document emanates. Unlike RFC 5141 which defines a fixed set of originator values, this specification uses a dynamic composition of publisher and copublishers joined by hyphens.

Current values include but are not limited to:

iso

International Organization for Standardization
iec

International Electrotechnical Commission
iso-iec

jointly developed by ISO and IEC
iso-cie

jointly developed by ISO and CIE
iso-astm

jointly developed by ISO and ASTM International
iso-ieee

jointly developed by ISO and IEEE
iso-iec-ieee

jointly developed by ISO, IEC, and IEEE

Additional copublisher combinations may be defined in future revisions.

type

Designates the ISO deliverable type. If the type element is not present, the classification is "International Standard".

data

Data (document type no longer published)
guide

Guide
isp

International Standardized Profile
iwa

International Workshop Agreement
pas

Publicly Available Specification
r

Recommendation (document type no longer published)
tr

Technical Report
ts

Technical Specification
tta

Technology Trends Assessment
dir

Directive
dir-sup

Directive Supplement
iwa-sup

IWA Supplement

RFC 5141 does not define dir, dir-sup, or iwa-sup. These are RFC 5141-bis extensions.

docnumber

The reference number assigned to the document by ISO and/or IEC.

partnumber

The reference number that identifies a part of a multipart standard. Omitting partnumber designates a multipart document in its entirety.

status / stage

Indicates the publication status of the document. When the status element is not present, the NSS refers to a published document.

RFC 5141-bis extends RFC 5141 by supporting typed stage abbreviations in addition to harmonized stage codes:

Harmonized stage code notation

stage-XX.XX where XX.XX is the harmonized stage code per ISO Guide 69:1999. An optional iteration suffix .vN identifies a specific project iteration.

stage-00.00

Preliminary work item
stage-20.00

New work item proposal
stage-30.00

Committee draft
stage-40.00

Draft International Standard
stage-50.00

Final Draft International Standard
stage-60.00

Published (not emitted for published documents)
Typed stage abbreviations (RFC 5141-bis)
PWI

Preliminary Work Item
NP

New Proposal / New Work Item Proposal
AWI

Approved Work Item
NWIP

New Work Item Proposal
WD

Working Draft
WDS

Working Draft Study
CD

Committee Draft
CDV

Committee Draft for Vote
DIS

Draft International Standard
FDIS

Final Draft International Standard
PDAM

Proposed Draft Amendment
DAM

Draft Amendment
FDAM

Final Draft Amendment
DCOR

Draft Corrigendum
FDCOR

Final Draft Corrigendum
CDTS

Committee Draft Technical Specification
DTS

Draft Technical Specification
FDTS

Final Draft Technical Specification
PRF

Proof

edition

ed-N designates a specific edition of the document. If no edition is specified, the NSS refers to the latest edition.

language

One or more ISO 639-1 alpha-2 language codes, comma-separated. RFC 5141-bis always emits language codes explicitly. Values include:

en

English
fr

French
ru

Russian
es

Spanish
ar

Arabic

Combinations are expressed as comma-separated lists: en,fr for bilingual, en,fr,ru for trilingual.

supplement

Designates a technical alteration of or addition to an ISO standard that does not result in a new edition or version.

Supplements are appended after the base document identifier and may be chained (e.g., a Corrigendum to an Amendment):

urn:iso:std:iso:9999:-1:ed-2:en:amd:1:cor:1
amd

Amendment — alters and/or adds technical provisions; subject to ballot
cor

Technical Corrigendum — corrects technical error or ambiguity; not balloted
sup

Supplement — generic supplement type
add

Addendum — (document type no longer published)

addition

An optional element that identifies a representation, extract, or related information set of an ISO document.

:tech…​

Committee-defined associated or embedded resource
(other)

Reserved for ISO Central Secretariat definitions

Examples

Basic identifiers

urn:iso:std:iso:9999:-1:ed-1:en
// 1st edition of ISO 9999-1, in English

urn:iso:std:iso-iec:tr:9999:-1:ed-1:en
// 1st edition of ISO/IEC TR 9999-1, in English

Undated references

urn:iso:std:iso:9001
// ISO 9001 (no date, edition, or language specified)

urn:iso:std:iso:8601:-1
// ISO 8601-1 (undated, with part number)

Status and stages

urn:iso:std:iso-iec:9075:-3:stage-95.99:ed-2:en
// Cancelled (withdrawn) 2nd edition of ISO/IEC 9075-3

urn:iso:std:iso-iec:9075:-3:stage-30.60:ed-4:en
// Draft 4th edition of ISO/IEC 9075-3

urn:iso:std:iso-iec:9075:-3:DIS:ed-4:en
// Same as above, using RFC 5141-bis typed stage abbreviation

Language handling

urn:iso:std:iso:9999:-1:ed-1:en
// English

urn:iso:std:iso:9999:-1:ed-1:en,fr
// English/French bilingual

urn:iso:std:iso:9999:-1:ed-1:en,fr,ru
// English/French/Russian trilingual

Supplements

urn:iso:std:iso:9999:-1:ed-2:en:amd:1
// Amendment 1 to the 2nd edition of ISO 9999-1, in English

urn:iso:std:iso:9999:-1:ed-2:en:amd:1:v2
// Corrected version (v2) of Amendment 1

urn:iso:std:iso:9999:-1:ed-2:en:amd:1:cor:1
// Corrigendum 1 to Amendment 1

urn:iso:std:iso-iec:13818:-1:amd:2016:v3:cor:2017:v1
// Amendment 3 (2016) with Corrigendum 1 (2017) to
// ISO/IEC 13818-1

Extended types (RFC 5141-bis)

urn:iso:std:iso:dir:iso
// ISO Directive

urn:iso:std:iso:dir-sup:iso:1:en
// ISO Directive Supplement, Part 1, in English

Identifier Uniqueness Considerations

Assignment of URNs for documents in the requested namespace is managed by the ISO Central Secretariat, which ensures that the assigned URNs are consistent with the ISO Directives for unique identification of ISO documents.

RFC 5141-bis supplements this by requiring that:

  • Typed stage abbreviations map unambiguously to harmonized stage codes.

  • Supplement chains have a defined ordering (outer supplement last in the NSS).

  • Language codes are always explicit, avoiding ambiguity from implicit defaults.

Identifier Persistence Considerations

Assigned URNs will not be reused and will remain valid beyond the lifecycle of the referenced resources. The status of a referenced resource may change (e.g., from draft to published, or from published to withdrawn).

Process for Identifier Resolution

A URN identifying an ISO document can be transformed to a valid HTTP URI by:

  1. Replacing the URN namespace prefix (urn:iso:) and the std: prefix with the domain name standards.iso.org.

  2. Replacing all occurrences of : within the identifier with /.

  3. Converting characters to lowercase.

Examples:

urn:iso:std:iso:9999:-1:ed-1:en
  -> http://standards.iso.org/iso/9999/-1/ed-1/en/

urn:iso:std:iso-iec:tr:9999:-1:ed-1:en
  -> http://standards.iso.org/iso-iec/tr/9999/-1/ed-1/en/

Rules for Lexical Equivalence

URNs are lexically equivalent if they are octet-by-octet equal after the following preprocessing:

  1. Normalize the case of the leading urn: token.

  2. Normalize the case of the NID.

  3. Normalize the case of any %-escaping.

  4. Normalize the case of all elements.

All URNs conforming to this specification use lowercase for all elements except typed stage abbreviations, which are case-insensitive per RFC 2141 Section 5.

Conformance with URN Syntax

No special considerations beyond RFC 2141.

Validation Mechanism

None specified.

Scope

Global.

Stage Code Evolution

Stage definitions in ISO are not static. The ISO technical management system introduces new stage types over time to reflect evolving working practices. This has implications for URN generation and parsing.

Dated Stage Codes

Following the approach used in RDF-based code lists (e.g., ISO’s published stage code vocabulary), stage definitions SHOULD be tracked with an effective date to distinguish when a stage was introduced.

Stage Abbreviation Effective Notes

Preliminary Work Item

PWI

1999

ISO Guide 69:1999

New Proposal

NP

1999

ISO Guide 69:1999

Approved Work Item

AWI

1999

ISO Guide 69:1999

Working Draft

WD

1999

ISO Guide 69:1999; harmonized codes 20.20, 20.60, 20.92, 20.93, 20.98, 20.99

Working Draft Study

WDS

2025-06

Introduced June 2025; harmonized codes 20.20, 20.60 (overlaps with WD)

Committee Draft

CD

1999

ISO Guide 69:1999

Committee Draft Technical Specification

CDTS

1999

Stage code cd applied to type ts

Draft International Standard

DIS

1999

ISO Guide 69:1999

Final Draft International Standard

FDIS

1999

ISO Guide 69:1999

Overlapping Harmonized Codes

Some stages share harmonized stage codes. For example, both WD and WDS use code 20.20. When parsing a URN that contains stage-20.20, implementations SHOULD resolve to the more general stage (WD) unless the typed abbreviation (WDS) is explicitly present in the URN.

Parsing Disambiguation Rules

When a harmonized stage code maps to multiple typed stages, the following rules apply:

  1. If the URN contains a typed stage abbreviation (stage-abbr), use the stage identified by that abbreviation directly.

  2. If the URN contains a harmonized code (stage-XX.XX), prefer the stage with the broader scope (more harmonized codes) over a specialized subset.

  3. Published stage codes (60.00, 60.60) resolve to "Proof" (PRF) or "Published" depending on context. Non-published stages take precedence over the published default for shared codes like 60.00.

Differences from RFC 5141

This specification extends RFC 5141 in the following ways:

Feature RFC 5141 RFC 5141-bis

Copublishers

Fixed set: iso, iec, iso-iec, iso-cie, iso-astm, iso-ieee

Dynamic: publisher *("-" copublisher) with extensible values

Document types

data, guide, isp, iwa, pas, r, tr, ts, tta

Extended with dir, dir-sup, iwa-sup

Stage notation

Harmonized stage codes only (stage-XX.XX)

Harmonized codes and typed stage abbreviations (WD, CD, DIS, etc.)

Supplement chains

Single level (amd/cor/add)

Multi-level nesting (Corrigendum to Amendment)

Language

May be omitted (English assumed)

Always explicit

Supplement types

amd, cor, add

Extended with sup (generic supplement)

Gap Analysis: RFC 5141 Issues and Resolutions

This appendix documents the issues identified in RFC 5141 and how RFC 5141-bis addresses each one. This analysis is provided to assist ISO in evaluating the proposed extensions.

# Status Issue and Resolution

1

Resolved

Missing copublishers. RFC 5141 defines a fixed set of originators (iso, iec, iso-iec, iso-cie, iso-astm, iso-ieee). RFC 5141-bis supports dynamic copublisher combinations via the publisher *("-" copublisher) pattern (see [originator]), enabling any combination (e.g., iso-iec-ieee, iso-astm, iso-iec-ieee-itu).

2

Resolved

Missing ability to have Corrigendum of Amendment. RFC 5141 only supports single-level supplements. RFC 5141-bis defines supplement chains with explicit ordering semantics (see [supplement]), enabling nested structures such as amd:1:cor:1 (Corrigendum 1 to Amendment 1).

3

Resolved

Missing supplement types for Guide, Directive, Directive Supplement. RFC 5141 defines amd, cor, and add only. RFC 5141-bis extends the type field with dir, dir-sup, and iwa-sup (see [type]), and adds sup as a generic supplement type.

4

Resolved

Missing ability to state stage of base identifier in supplements. RFC 5141 provides no mechanism to include the base document’s stage in a supplement URN. RFC 5141-bis supports typed stage abbreviations (see [statusstage]) and harmonized stage codes on the base document, preserving the stage information in supplement URNs.

5

Resolved

Missing support for new stage types (WDS, CDTS). RFC 5141 uses only harmonized stage codes. RFC 5141-bis adds typed stage abbreviations (see [statusstage]) including WDS (Working Draft Study, introduced 2025-06) and CDTS (Committee Draft Technical Specification), with dated stage code tracking (see [Stage Code Evolution]).

6

Resolved

Missing support for new document types (IWA). RFC 5141 lists data, guide, isp, iwa, pas, r, tr, ts, tta. RFC 5141-bis extends this with dir, dir-sup, and iwa-sup (see [type]).

All six identified gaps have been resolved in the RFC 5141-bis specification and implemented in the PubID software library with full test coverage. The implementation is available as open-source software to facilitate adoption by ISO Central Secretariat.

References

Normative References

  • [ISO/IEC Directives Part 1] — International Organization for Standardization, "Procedures for the technical work".

  • [ISO/IEC Directives Part 2] — International Organization for Standardization, "Rules for the structure and drafting of International Standards".

  • [RFC 2141] — Moats, R., "URN Syntax", May 1997.

  • [RFC 5141] — Goodwin, J., Apel, H., "A URN Namespace for ISO", March 2008.

  • [RFC 5234] — Crocker, D., Overell, P., "Augmented BNF for Syntax Specifications: ABNF", January 2008.

Informative References

  • [ISO Guide 69:1999] — "Harmonized Stage Code system (Edition 2) — Principles and guidelines for use".

  • [ISO 639-1:2002] — "Codes for the representation of names of languages — Part 1: Alpha-2 code".

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