Date and time — Reference time scales CC/WD 34100:2019341002019-02-02 CalConnect committee CalConnect DATETIME CalConnect 12019-02-02enworking-draft2019 CalConnect standardcc false 2222

© 2019 The Calendaring and Scheduling Consortium, Inc.

 Warning for Drafts

This document is not a CalConnect Standard. It is distributed for review and comment, and is subject to change without notice and may not be referred to as a Standard. Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to provide supporting documentation.

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from the address below.

The Calendaring and Scheduling Consortium, Inc.

4390 Chaffin Lane
McKinleyville
California 95519
United States of America


www.calconnect.org

 Foreword

The Calendaring and Scheduling Consortium (“CalConnect”) is a global non-profit organization with the aim to facilitate interoperability of collaborative technologies and tools through open standards.

CalConnect works closely with international and regional partners, of which the full list is available on our website ().

The procedures used to develop this document and those intended for its further maintenance are described in the CalConnect Directives.

In particular the different approval criteria needed for the different types of CalConnect documents should be noted. This document was drafted in accordance with the editorial rules of the CalConnect Directives.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CalConnect shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be provided in the Introduction.

Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.

This document was prepared by Technical Committee DATETIME.

 Introduction General

This international standard describes the concepts, data model representations, and universally applicable coded representations of reference time scales and their authorities.

It belongs to the same family of standards as and , the international standards for date and time representation.

This international standard provides code lists that facilitates the representation of a reference time scale. Such representation is crucial in knowing the basis of a timestamp, for example, in the fields of legal metrology, meteorology, astronomy and geoinformatics.

 Concepts

This document aims to standardize the concept of a reference time scale, its parameters and associated concepts for the use of the international community.

In particular, these concepts are defined in this document:

  • reference time scale; and

  • reference time scale authority.

 Data models

This document provides a number of data models that defines reference time scales and related concepts in fine resolution, allowing compliant implementations to be able to interoperate.

 Coded representations

This international standard establishes codes that represent the following attributes, current or in the past, on the basis of data obtained from official sources:

  • names of reference time scales; and

  • names of reference time scale authorities.

 Registration authority of code lists

This document specifies a registration authority that manages and disseminates the code lists required by this document.

The registration authority is not meant to replace existing computer reference time scale databases, but meant to serve authoritative reference time scale information created by the reference time scale authorities, and can be used as an upstream information source to synchronize existing reference time scale databases.

The mechanism of reference time scale registration given in this international standard empowers reference time scale authorities to publish digital definitions of their reference time scales themselves, therefore allowing users to directly obtain authoritative reference time scale information from the reference time scale authorities.

 Priority for practice

This document aims to provide interoperable representations and mechanisms for the use and management of reference time scales.

It does not express any opinion whatsoever concerning the legal status of any country, dependency, or other area named herein, or concerning its frontiers or boundaries.

 Scope

This document describes the concepts and definitions related to time scales, including:

  • time scales; and

  • time scale authorities.

This document also establishes codes that represent the following attributes, current or in the past, on the basis of data obtained from official sources:

  • names of time scales; and

  • names of time scale authorities.

This document specifies a registration authority that manages and disseminates the code lists required by this document.

This document is intended for use in any application requiring the expression of time scale names and time scale authority names in coded form. It also includes basic guidelines for its implementation and maintenance.

Methods of using codes provided in this document for indication of time scales or related concepts are not covered in this document.

 Terms and definitions

For the purposes of this document, the terms and definitions given in and the following apply.

code

set of data transformed or represented in different forms according to a pre-established set of rules

 3.1.13.10 code element

the result of applying a code to an element of a coded set

 21215552 reference time scale

time scale of generally agreed definition and rules used as a reference

Common reference quantity measurements for time scales include atomic oscillations, earth rotation and celestial motion.

The reference time scale is not always legally UTC in all countries.

Reference time scales in use other than UTC include: UT, TAI, GMT, GPS system time, Galileo system time, BeiDou system time, LORAN station system time.

 civil time scale

time scale based on a reference time scale () with an offset determined through administration

 time scale authority

entity assigned to oversee determination and regulation of a reference time scale ()

The GMT time scale was published by BIH until GMT was superseded by UT, which is now published by IERS.

The reference time scale for a country is generally set by a national time lab. For example, NIST is a time scale authority since 1967-04-28 21:00.

BIPM Circular T provides a list of the national time authorities who are members and who participate in the construction of TAI and UTC.

BIPM is the time scale authority of UTC and TAI.

NIST is the time scale authority of UTC(NIST).

 time scale identifier

code () that represents indicates a time scale

 time scale authority identifier

code () that represents indicates a time scale authority ()

 official time scales authority

governmental agency or office with the responsibility of a time scale authority () within a country, jurisdiction, or assigned territory

The US Department of Transport is an official time scale authority carrying authority of the United States.

 unofficial time scale authority

time scale authority () that is not an official time scale authority () or international time scale authority ()

The University of California Observatories is an unofficial time scale authority.

 international time scale authority

time scale authority () that operates under international scope and whose decisions for reference time scales () management are made with international participation

The BIPM is an international time scale authority.

 language identifier

information which indicates the name of a language

 3.3 script

combination of characters used to represent the name of a script

 3.8 ISO 3166 code

identifier provided by the ISO 3166 series of standards listing of country names with their representations by code elements

 3.3

term changed to “ISO 3166 code” to reflect origin.

 country name

name of a country, dependency, or other area of particular geopolitical interest

 3.4 Common data attributes General Usage of ISO 3166 code elements

The alpha-2 code list is used in this document to represent entities or data to indicate names of country or regions.

These alpha-2 codes from are used in this document for the following meanings that differ from their assignment in :

  1. AA represents entities that are international in nature (such as the BIPM) or data intended for international application (such as the TODO NEED EXAMPLE), (assigned as a “user-assigned code element” in 8.1.3);

  2. XZ represents entities that are located in international waters or data intended for application at international waters (assigned as a “user-assigned code element” in 8.1.3);

    3. The usage of XZ echos the identical practice of .

  1. ZZ represents entities not operating under or endorsed officially by UN member states, or data intended for unofficial use (assigned as a “user-assigned code element” in 8.1.3);

  2. the range XA to XZ is reserved for user private use, such as to represent entities or data not provided by this document and not meant to be used publicly (assigned as “user-assigned code elements” in 8.1.3);

  3. EU represents entities that operate under authority of the European Union, or data that is intended to apply to the European Union (as listed an “exceptionally reserved” element at );

  4. UN represents entities that operate under authority of the United Nations or its specialized agencies, or data that is intended for United Nations members or its specialized agencies (as listed an “exceptionally reserved” element at ).

 Data models

The following data models are common to the data models specified in and .

Localization

LocalizationString represents a single string.

LocalizationCollection represents a collection of localized strings.

The script tag uses script codes from and language codes from .

skinparam Dpi 150 skinparam Monochrome false skinparam LineType ortho hide circle /' skinparam CircledCharacterRadius 0 '/ /' skinparam CircledCharacterFontSize 0 '/ skinparam Default { TextAlignment center FontName Helvetica } skinparam Class { AttributeIconSize 0 BackgroundColor White ArrowColor Black BorderColor Black FontStyle bold StereotypeFontSize 10 } skinparam Rectangle { BackgroundColor White ArrowColor Black BorderColor Black FontStyle bold FontSize 11 StereotypeFontSize 10 } skinparam Object { BackgroundColor White ArrowColor Black BorderColor Black FontStyle bold FontSize 11 StereotypeFontSize 10 } skinparam Entity { StereotypeFontSize 10 } '******* CLASS DEFINITION ********************************************* class LocalizedStringCollection { +content: LocalizedString[1..*] +localetag: LocalizationTag[0..1] } class LocalizationTag { +language: iso639Code +script: iso15924Code } class LocalizedString { +content: String +localetag: LocalizationTag[0..1] } class iso639Code <<dataType>>{ } class iso15924Code <<dataType>>{ } LocalizedStringCollection <-- LocalizationTag LocalizedStringCollection <-- LocalizedString LocalizedString <-- LocalizationTag LocalizationTag <-- iso639Code LocalizationTag <-- iso15924Code Reference time scale authority General

A reference time scale authority is a competent authority that creates, publishes and/or manages definitions of reference time scales and their changes.

 Requirements of a reference time scale authority

A reference time scale authority must be competent.

Competency

A competent reference time scale authority is one that has standardized processes surrounding the management of the reference time scales, covering at least the following processes:

  1. Planning of reference time scales, including the process of designing and defining a reference time scale.

  2. Performing changes to reference time scales are well planned and executed in a manner that is considerate of reference time scale users.

  3. Public announcement and dissemination of its reference time scale.

  4. Authoritative announcement of current time under a reference time scale under its management.

  5. Allows a public review period for people affected by reference time scales under its management prior to enactment.

 Types of reference time scale authorities International reference time scale authorities

International reference time scale authorities are listed with the code AA.

It is defined as a reference time scale authority that:

  1. operates under international scope; and

  2. whose decisions for reference time scale management are made with international participation.

The BIPM is an international reference time scale authority.

 Official reference time scale authority

An official reference time scale authority is appointed by a local or regional governmental body, whereas the authority for appointment comes from a United Nations member state.

The US NIST with the code us-nist, publishes reference time scales that apply to the territory of United States.

 Unofficial reference time scale authority

An unofficial reference time scale authority is a reference time scale authority not appointed by a United Nations member state. These authorities must be competent with regards to reference time scale management and can publish reference time scales used by communities.

 Registration of reference time scale authorities

The ISO 34100/AG is tasked with managing a list of reference time scale authorities.

 Data model and attributes General skinparam Dpi 150 skinparam Monochrome false skinparam LineType ortho hide circle /' skinparam CircledCharacterRadius 0 '/ /' skinparam CircledCharacterFontSize 0 '/ skinparam Default { TextAlignment center FontName Helvetica } skinparam Class { AttributeIconSize 0 BackgroundColor White ArrowColor Black BorderColor Black FontStyle bold StereotypeFontSize 10 } skinparam Rectangle { BackgroundColor White ArrowColor Black BorderColor Black FontStyle bold FontSize 11 StereotypeFontSize 10 } skinparam Object { BackgroundColor White ArrowColor Black BorderColor Black FontStyle bold FontSize 11 StereotypeFontSize 10 } skinparam Entity { StereotypeFontSize 10 } class AuthorityInfo { +authorityCode: String +uri: Uri +name: LocalizedStringCollection +iso3166Code: iso3166Code +description: LocalizedStringCollection ' +publicKey: PublicKey } class OfficialAuthorityInfo extends AuthorityInfo { } class InternationalAuthorityInfo extends AuthorityInfo { +iso3166Code: iso3166Code = AA } class UnofficialAuthorityInfo extends AuthorityInfo { +iso3166Code: iso3166Code = ZZ } 'class SignatureInfo { ' +signature: String ' +algorithm: iso14888Oid ' +publicKeyUri: Uri '} ' 'class PublicKey { ' +algorithm: iso14888Oid ' +content: String ' +uri: Uri ' +validity: ValidityInfo '} 'class iso14888Oid <<dataType>>{ ' '} '******* CLASS RELATIONS ********************************************** 'SignatureInfo <-- iso14888Oid 'AuthorityInfo <-- PublicKey Reference time scale authority code

A code that represents the reference time scale authority.

 ISO 3166 alpha-2-code

A code that represents the jurisdictional authority of the reference time scale authority.

NIST is the authoritative reference time scale authority of the United States, with the code US.

 English short name

The identifiable short name that uniquely identifies the reference time scale authority within its ISO 3166 code.

 Abbreviation

The identifiable abbreviation used for the reference time scale authority.

 Remarks

Any further notes.

 Code and identifier Principles for inclusion in the list of reference time scale authorities List

The list of reference time scale authorities in this document includes known authorities from regions consisting of codes through official sources.

 Source of names

Names and abbreviations of reference time scales are obtained from the reference time scale authorities or official sources.

 Overlaps

Some reference time scale authorities cover areas that have also been coded separately where an interchange requirement justifies a separate code element; the entries are therefore not mutually exclusive.

The China National Time Service Center, with the code cn-ntsc, publishes reference time scales that contribute to the UTC time scale.

The Hong Kong Observatory with the code hk-hko, publishes reference time scales that contribute to the UTC time scale.

 Current status of names

Reference time scale authorities listed in this document are intended to reflect the current situation, at the time of issue of the latest update of this document.

 Principles for allocation of code elements Relationship with names

The principle behind the alphabetic codes for reference time scale authorities is a visual association between the reference time scale authorities and their corresponding code elements.

In applying this principle, the code elements have generally been assigned on the basis of the abbreviated names of the reference time scale authorities, thus avoiding, wherever possible, any reflection of their political status.

Official reference time scale identifiers are in the following format:

[iso-3166-code]-[reference-time-scale-authority-identifier]

hk-hko for the Hong Kong Observatory.

The private code point AA is used as a prefix for international reference time scales.

aa-[reference-time-scale-authority-identifier]

aa-bipm for the BIPM.

The private code point ZZ is used as a prefix for all unofficial reference time scale authorities.

In terms of coding, official reference time scale authority-identifiers are in the following format:

zz-[reference-time-scale-authority-identifier] Construction of the alphabetic code

The following rules are to be adhered to for the assignment of the alphabetic code:

  • The alphabetic code uses combinations, in upper case, of a maximum of 16 letters of the 26-character Latin alphabet with the “dash” (-).

  • To encourage descriptive and distinguishable alphabetic names, the minimum length of the reference time scale identifier without the code is 3 letters.

  • The specific code prefix of XX is reserved and is used as the prefix of user-assignable reference time scale codes.

 User assigned code elements

If users need code elements to represent reference time scales not included in the reference time scale registry, the code prefix of XX can be used, being a reserved code point XX for private user assignment.

The code length for the reference time scale identifier must be 3 or more letters.

Such reference time scale identifiers are in the following format:

xx-[reference-time-scale-authority-identifier]

Users are advised that the above series of codes are not universals, those code elements are not compatible between different entities.

 List of reference time scale authorities and their code elements

The list of items composing the content of the country code is initially defined in . Additional and new entries will be listed by the ISO 34100/AG.

Data attributes provided in the list are defined in .

 Reference time scale General

Reference time scales are created and managed by time authorities.

Reference time scales can contain time modification records. For example, the UTC time scale provides a list of leap seconds that adjusted UTC time since its inception.

 Types of reference time scales International reference time scales

International reference time scales are reference time scales that apply internationally without regard to geolocation.

UTC and TAI are international reference time scales.

 Official reference time scales

Official reference time scales are created by official reference time scale authorities and international reference time scale authorities.

 Unofficial reference time scales

Unofficial reference time scales can be created by any reference time scale authority.

 Registration of reference time scales

The ISO 34100/AG is tasked with managing a list of reference time scales.

 Data model and attributes General skinparam Dpi 150 skinparam Monochrome false skinparam LineType ortho hide circle /' skinparam CircledCharacterRadius 0 '/ /' skinparam CircledCharacterFontSize 0 '/ skinparam Default { TextAlignment center FontName Helvetica } skinparam Class { AttributeIconSize 0 BackgroundColor White ArrowColor Black BorderColor Black FontStyle bold StereotypeFontSize 10 } skinparam Rectangle { BackgroundColor White ArrowColor Black BorderColor Black FontStyle bold FontSize 11 StereotypeFontSize 10 } skinparam Object { BackgroundColor White ArrowColor Black BorderColor Black FontStyle bold FontSize 11 StereotypeFontSize 10 } skinparam Entity { StereotypeFontSize 10 } '******* CLASS DEFINITION ********************************************* class ReferenceTimeScale { +id: Uid +authority: AuthorityInfo +name: LocalizedStringCollection +description: LocalizedStringCollection ' +leapSeconds: LeapSecondRecord[0..*] } 'class LeapSecondRecord { ' +time: iso8601DateTime ' +seconds: Integer '} '******* NOTES ******************************************************** 'ReferenceTimeScale <|-down- LeapSecondRecord Reference time scale code

A code that represents the reference time scale.

 ISO 3166 alpha-2-code

A code that represents the geographic applicability of the reference time scale.

UTC time applies globally with the code aa.

 Internationally recognized short name

The internationally recognized short name that uniquely identifies the reference time scale.

 Abbreviation

The identifiable abbreviation used for the reference time scale. This is optional.

 Reference time scale authority code

A code that represents the reference time scale authority who manages this reference time scale.

 Remarks

Any further notes.

 Leap seconds

A record of positive or negative leap seconds applied to the reference time scale at the described date.

UTC leap seconds are provided since its inception in 1972.

Leap seconds does not apply to the GMT reference time scale.

 Code and identifier Principles for inclusion in the list of reference time scales List

The list of reference time scales in this document includes known reference time scales from official sources.

 Source of names

Names and abbreviations of reference time scales are obtained from the reference time scale authorities or other official sources.

 Overlaps

Some reference time scales cover areas that have also been coded separately where an interchange requirement justifies a separate code element; the entries are therefore not mutually exclusive.

aa-utc applies internationally.

us-gps applies to the United States.

 Current status of names

Reference time scales listed in this document are intended to reflect the current situation, at the time of issue of the latest update of this document.

 Principles for allocation of code elements Relationship with names

Official reference time scale identifiers are in the following format:

[iso-3166-code]-[reference-time-scale-identifier]

hk-utchk for the UTC(Hong Kong) reference time scale managed by the Hong Kong Observatory.

The private code point AA is used as a prefix for international reference time scales.

aa-[reference-time-scale-identifier]

aa-utc for the UTC reference time scale managed by the BIPM.

The private code point ZZ is used as a prefix for all unofficial reference time scales.

In terms of coding, official reference time scale identifiers are in the following format:

zz-[reference-time-scale-authority-identifier]-[reference-time-scale-identifier] Construction of the alphabetic code

The following rules are to be adhered to for the assignment of the alphabetic code:

  • The alphabetic code uses combinations, in upper case, of a maximum of 16 letters of the 26-character Latin alphabet with the “dash” (-).

  • To encourage descriptive and distinguishable alphabetic names, the minimum length of the reference time scale identifier without the code is 3 letters.

  • The specific code prefix of XX is reserved and is used as the prefix of user-assignable reference time scale codes.

 User assigned code elements

If users need code elements to represent reference time scales not included in the reference time scale registry, the code prefix of XX can be used, being a reserved code point XX for private user assignment.

The code length for the reference time scale identifier must be 3 or more letters.

Such reference time scale identifiers are in the following format:

xx-[reference-time-scale-authority-identifier]-[reference time scale-identifier]

Users are advised that the above series of codes are not universals, those code elements are not compatible between different entities.

 List of reference time scale and their code elements

The list of items composing the content of the country code is initially defined in . Additional and new entries will be listed by the ISO 34100/AG.

Data attributes provided in the list is defined in .

 Registration Registration authority (ISO 34100/RA)

A registration authority (ISO 34100/AG) has been appointed to operate under guidelines provided in this Annex. It has been entrusted with the following functions:

  1. to add and eliminate reference time scales and their authorities, in accordance with the rules in this document;

  2. to advise users and ISO member bodies regarding application of the codes;

  3. to update and disseminate list of reference time scales, their authorities and their definitions;

  4. to maintain a reference list of all reference time scales, their authorities and definitions;

  5. to publish changes made to such information;

  6. to administer the reservation of codes related to the list of reference time scales and their authorities.

Changes to this part of ISO 34100 are decided by the ISO 34100/AG and become effective immediately upon publication.

The criteria provided in to 6.5 shall be observed by the ISO 34100/AG for changes to the list of country names in this part of ISO 34100, and their code elements, and for reservations of code elements.

 Advisory group (ISO 34100/AG)

An advisory group (ISO 34100/AG) has been appointed to ensure the operations of the registration authority (ISO 34100/RA) are in accordance with guidelines provided in this Annex.

 Addition to the list of reference time scale authorities

Additions to the list of reference time scales authorities shall be made on the basis of information from a member of the United Nations, or upon the request of a member of ISO 34100/AG.

In the latter case, the ISO 34100/AG will decide upon the addition, on the basis of the justification given for the actual requirements for international interchange. Code elements will be allocated accordingly.

Additions to the official and international time scale authorities require additional criteria:

  • An official time scale authority must be endorsed by a body receiving direct authority by a member of the United Nations.

  • An international time scale authority must be endorsed by an international standardization body in liaison with the ISO 34100/AG.

 Addition to the list of reference time scales

Additions to the list of reference time scales shall be made only by the appropriate registered authority.

 Deletion from the list of reference time scale authorities

Deletion from the list of reference time scales authorities shall be made on the basis of information from a member of the United Nations, or upon the request of a member of ISO 34100/AG.

The ISO 34100/AG will decide upon the deletion, on the basis of the information received. The corresponding code element is reserved.

 Deletion of elements from the list of reference time scales

Deletion from the list of reference time scales shall be made only by the authority that registered the element.

The ISO 34100/AG will decide upon the deletion, on the basis of the information received. The corresponding code element is reserved.

 Alterations to elements on list of reference time scales

Alterations to a registered element shall be made only by the authority that registered the element.

A significant change of name may require the ISO 34100/AG to change the alpha code element concerned. The ISO 34100/AG, however, shall endeavor to maintain stability in the list of code elements.

 Advice regarding use of country code elements

The ISO 34100/AG is available for consultation and assistance on the use of country names in coded form. The ISO 34100/AG does not administer or maintain lists of user-assigned code elements

 Alphabetical list of official reference time scale authorities in English and their code elements
Reference time scale authority identifier ISO 3166 Alpha-2 Code English short name Abbreviation Remarks
aa-bipm aa International Bureau of Weights and Measures BIPM
aa-iers aa International Earth Rotation and Reference Systems Service IERS
us-afspc us United States Air Force Space Command AFSPC
us-nist us United States National Institute of Standards and Technology NIST
us-dhs us United States Department of Homeland Security DHS
eu-esa eu European Space Agency ESA
eu-gsa eu European Global Navigation Satellite Systems Agency GSA
ru-rc ru Roscosmos State Corporation for Space Activities Roscosmos
cn-cnsa cn China National Space Administration CNSA
Alphabetical list of reference time scale names in English and their code elements
Reference time scale identifier ISO 3166 Alpha-2 Code English short name Abbreviation Authority Remarks
aa-gmst aa Greenwich Mean Sidereal Time GMST aa-iers
aa-lat aa Local Apparent Time LAT none
aa-lmt aa Local Mean Time LMT none
aa-tai aa International Atomic Time TAI aa-bipm
aa-tcb aa Barycentric Coordinate Time TCB aa-iers
aa-tcg aa Geocentric Coordinate Time TCG aa-iers
aa-tdb aa Barycentric Dynamical Time TDB aa-iers
aa-tt aa Terrestrial Time TT aa-iers Previously TDT
aa-ut aa Universal Time UT aa-iers Previously Greenwich Mean Time (GMT)
aa-utc aa Coordinated Universal Time UTC aa-bipm
cn-bds cn BeiDou time BDS cn-cnsa
eu-galileo eu Galileo time Galileo eu-esa, eu-gsa
ru-glonass ru Global Navigation Satellite System time GLONASS ru-rc
us-gps us Global Positioning System Time GPS us-afspc
Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

2026-05-13 Date and time Representations for information interchange Part 1: Basic rules Date and time — Representations for information interchange — Part 1: Basic rules Date et heure Représentations pour l’échange d’information Partie 1: Règles de base Date et heure — Représentations pour l’échange d’information — Partie 1: Règles de base https://www.iso.org/standard/70907.html https://www.iso.org/obp/ui/en/#!iso:std:70907:en https://www.iso.org/contents/data/standard/07/09/70907.detail.rss ISO 8601-1:2019 ISO 8601-1:2019(E) urn:iso:std:iso:8601:-1:stage-90.92 8601 2019-02 International Organization for Standardization ISO www.iso.org committee International Organization for Standardization Processes, data elements and documents in commerce, industry and administration ISO/TC 154 ISO 1 en fr This document specifies representations of dates of the Gregorian calendar and times based on the 24-hour clock, as well as composite elements of them, as character strings for use in information interchange. It is also applicable for representing times and time shifts based on Coordinated Universal Time (UTC). This document excludes the representation of date elements from non-Gregorian calendars or times not from the 24-hour clock. This document does not address character encoding of representations specified in this document. This document specifies representations of dates of the Gregorian calendar and times based on the 24-hour clock, as well as composite elements of them, as character strings for use in information interchange. It is also applicable for representing times and time shifts based on Coordinated Universal Time (UTC). This document excludes the representation of date elements from non-Gregorian calendars or times not from the 24-hour clock. This document does not address character encoding of representations specified in this document. 90 92 2019 ISO ISO 8601:2004 ISO 8601:2004 ISO/AWI 8601-1 ISO/AWI 8601-1 Geneva 2026-05-13 Date and time Representations for information interchange Part 2: Extensions Date and time — Representations for information interchange — Part 2: Extensions Date et heure Représentations pour l’échange d’information Partie 2: Extensions Date et heure — Représentations pour l’échange d’information — Partie 2: Extensions https://www.iso.org/standard/70908.html https://www.iso.org/obp/ui/en/#!iso:std:70908:en https://www.iso.org/contents/data/standard/07/09/70908.detail.rss ISO 8601-2:2019 ISO 8601-2:2019(E) urn:iso:std:iso:8601:-2:stage-90.92 8601 2019-02 International Organization for Standardization ISO www.iso.org committee International Organization for Standardization Processes, data elements and documents in commerce, industry and administration ISO/TC 154 ISO 1 en fr This document specifies additional representations of dates of the Gregorian calendar and times based on the 24-hour clock that extend the basic rules and composite elements of those defined in ISO 8601-1. These representations are specified as character strings for use in information interchange. It is also applicable for representing times and time shifts based on Coordinated Universal Time (UTC). These extensions include: — uncertain or approximate dates, or dates with portions unspecified; — extended time intervals; — divisions of a year; — sets and choices of calendar dates; — grouped time scale units; — repeat rules for recurring time intervals; and — date and time arithmetic. This document excludes the representation of date elements from non-Gregorian calendars, or times not from the 24-hour clock. This document does not address character encoding of representations specified in this document. This document specifies additional representations of dates of the Gregorian calendar and times based on the 24-hour clock that extend the basic rules and composite elements of those defined in ISO 8601-1. These representations are specified as character strings for use in information interchange. It is also applicable for representing times and time shifts based on Coordinated Universal Time (UTC). These extensions include: — uncertain or approximate dates, or dates with portions unspecified; — extended time intervals; — divisions of a year; — sets and choices of calendar dates; — grouped time scale units; — repeat rules for recurring time intervals; and — date and time arithmetic. This document excludes the representation of date elements from non-Gregorian calendars, or times not from the 24-hour clock. This document does not address character encoding of representations specified in this document. 90 92 2019 ISO ISO 8601:2004 ISO 8601:2004 ISO/AWI 8601-2 ISO/AWI 8601-2 Geneva 2026-05-13 Codes for the representation of names of languages Part 1: Alpha-2 code Codes for the representation of names of languages — Part 1: Alpha-2 code Codes pour la représentation des noms de langue Partie 1: Code alpha-2 Codes pour la représentation des noms de langue — Partie 1: Code alpha-2 https://www.iso.org/standard/22109.html https://www.iso.org/contents/data/standard/02/21/22109.detail.rss ISO 639-1:2002 ISO 639-1:2002(E) urn:iso:std:iso:639:-1:stage-95.99 639 2002-07 International Organization for Standardization ISO www.iso.org committee International Organization for Standardization Terminology workflow and language coding ISO/TC 37/SC 2 ISO 1 en fr This part of ISO 639 provides a code consisting of language code elements comprising two-letter language identifiers for the representation of names of languages. The language identifiers according to this part of ISO 639 were devised originally for use in terminology, lexicography and linguistics, but may be adopted for any application requiring the expression of language in two-letter coded form, especially in computerized systems. The alpha-2 code was devised for practical use for most of the major languages of the world that are not only most frequently represented in the total body of the world’s literature, but which also comprise a considerable volume of specialized languages and terminologies. Additional language identifiers are created when it becomes apparent that a significant body of documentation written in specialized languages and terminologies exists. Languages designed exclusively for machine use, such as computer-programming languages, are not included in this code. La présente partie de l’ISO 639 fournit un code composé de codets de langue formés avec des indicatifs de langue à deux lettres pour la représentation des noms de langue. Les indicatifs de langue figurant dans la présente partie de l’ISO 639 ont été conçus principalement pour être utilisés en terminologie, lexicographie et linguistique mais peuvent être adaptés à toute autre application dans laquelle il est nécessaire d’exprimer une langue sous la forme d’un code à deux lettres, notamment dans le cadre des systèmes informatiques. Le code alpha-2 a été créé pour un usage pratique pour la plupart des grandes langues du monde qui ne sont pas seulement les plus souvent représentées dans le corpus de la littérature mondiale, mais pour lesquelles il existe également un volume considérable de langues de spécialité et de terminologies. De nouveaux indicatifs de langue sont créés lorsqu’il devient évident qu’il existe un corpus significatif de documentation écrite dans des langues de spécialité et des terminologies. Les langages créés pour être utilisés exclusivement par des machines, comme les langages de programmation, ne sont pas inclus dans le présent code. 95 99 2002 ISO ISO 639:1988 ISO 639:1988 Geneva 2026-05-13 Information and documentation Codes for the representation of names of scripts Information and documentation — Codes for the representation of names of scripts Information et documentation Codes pour la représentation des noms d’écritures Information et documentation — Codes pour la représentation des noms d’écritures https://www.iso.org/standard/29546.html https://www.iso.org/contents/data/standard/02/95/29546.detail.rss ISO 15924:2004 ISO 15924:2004(E) urn:iso:std:iso:15924:stage-95.99 15924 2004-02 International Organization for Standardization ISO www.iso.org committee International Organization for Standardization Information and documentation ISO/TC 46 ISO 1 en fr ISO 15924:2004 provides a code for the presentation of names of scripts. The codes were devised for use in terminology, lexicography, bibliography and linguistics, but they may be used for any application requiring the expression of scripts in coded form. ISO 15924:2004 also includes guidance on the use of script codes in some of these applications. L’ISO 15924:2004 fournit un code équivalent aux noms d’écritures.Les codets sont conçus principalement pour être utilisés en terminologie, en lexicographie, en bibliographie et en linguistique, mais ils conviennent également à tous les cas nécessitant l’identification des écritures au moyen d ‘un code. L’ISO 15924:2004 contient également des renseignements sur la façon d’employer les codets dans certains de ces cas. 95 99 2004 ISO Geneva 2026-05-13 Codes for the representation of names of countries and their subdivisions Part 1: Country codes Codes for the representation of names of countries and their subdivisions — Part 1: Country codes Codes pour la représentation des noms de pays et de leurs subdivisions Partie 1: Codes de pays Codes pour la représentation des noms de pays et de leurs subdivisions — Partie 1: Codes de pays https://www.iso.org/standard/63545.html https://www.iso.org/contents/data/standard/06/35/63545.detail.rss ISO 3166-1:2013 ISO 3166-1:2013(E) urn:iso:std:iso:3166:-1:stage-95.99 3166 2013-11 International Organization for Standardization ISO www.iso.org committee International Organization for Standardization Information and documentation ISO/TC 46 ISO 3 en fr ISO 3166-1:2013 is intended for use in any application requiring the expression of current country names in coded form; it also includes basic guidelines for its implementation and maintenance. L’ISO 3166-1:2013 est destinée à toute application nécessitant l’expression des noms de pays sous une forme codée; elle contient également des principes directeurs pour sa mise en application et sa mise à jour. 95 99 2013 ISO ISO 3166-1:2006 ISO 3166-1:2006 ISO 3166-1:2006/Cor 1:2007 ISO 3166-1:2006/Cor 1:2007 Geneva Bibliography 2026-05-13 Quantities and units Part 1: General Quantities and units — Part 1: General Grandeurs et unités Partie 1: Généralités Grandeurs et unités — Partie 1: Généralités https://www.iso.org/standard/30669.html https://www.iso.org/contents/data/standard/03/06/30669.detail.rss ISO 80000-1:2009 ISO 80000-1:2009(E) urn:iso:std:iso:80000:-1:stage-95.99 80000 2009-11 International Organization for Standardization ISO www.iso.org committee International Organization for Standardization Quantities and units ISO/TC 12 ISO 1 en fr ISO 80000-1:2009 gives general information and definitions concerning quantities, systems of quantities, units, quantity and unit symbols, and coherent unit systems, especially the International System of Quantities, ISQ, and the International System of Units, SI. The principles laid down in ISO 80000-1:2009 are intended for general use within the various fields of science and technology and as an introduction to other parts of the Quantities and units series. Ordinal quantities and nominal properties are outside the scope of ISO 80000-1:2009. L’ISO 80000‑1:2009 donne des informations générales et des définitions à propos des grandeurs, des systèmes de grandeurs, des unités, des symboles de grandeurs et d’unités, et des systèmes cohérents d’unités, notamment le Système international de grandeurs (ISQ) et le Système international d’unités (SI). Les principes établis dans l’ISO 80000‑1:2009 sont prévus pour un usage général dans les divers domaines scientifiques et techniques, ainsi qu’en introduction aux autres parties de la présente Norme internationale. Les grandeurs ordinales et les propriétés qualitatives sont hors du domaine d’application de l’ISO 80000‑1:2009. 95 99 2009 ISO ISO 31-0:1992 ISO 31-0:1992 ISO 31-0:1992/Amd 1:1998 ISO 31-0:1992/Amd 1:1998 ISO 31-0:1992/Amd 2:2005 ISO 31-0:1992/Amd 2:2005 ISO 1000:1992 ISO 1000:1992 ISO 1000:1992/Amd 1:1998 ISO 1000:1992/Amd 1:1998 Geneva 2026-05-13 Quantities and units Part 3: Space and time Quantities and units — Part 3: Space and time Grandeurs et unités Partie 3: Espace et temps Grandeurs et unités — Partie 3: Espace et temps https://www.iso.org/standard/31888.html https://www.iso.org/contents/data/standard/03/18/31888.detail.rss ISO 80000-3:2006 ISO 80000-3:2006(E) urn:iso:std:iso:80000:-3:stage-95.99 80000 2006-03 International Organization for Standardization ISO www.iso.org committee International Organization for Standardization Quantities and units ISO/TC 12 ISO 1 en fr ISO 80000-3:2006 gives names, symbols and definitions for quantities and units of space and time. Where appropriate, conversion factors are also given. L’ISO 80000-3:2006 spécifie les noms, les symboles et les définitions des grandeurs et unités d’espace et de temps. Des facteurs de conversion sont également indiqués, s’il y a lieu. 95 99 2006 ISO ISO 31-1:1992 ISO 31-1:1992 ISO 31-1:1992/Amd 1:1998 ISO 31-1:1992/Amd 1:1998 ISO 31-2:1992 ISO 31-2:1992 ISO 31-2:1992/Amd 1:1998 ISO 31-2:1992/Amd 1:1998 ISO 80000-3:2019 ISO 80000-3:2019 2019-10-22 Geneva tz database, IANA, last accessed: TODO IANA tz database en 2026-05-13 Information and documentation Foundation and vocabulary Information and documentation — Foundation and vocabulary Information et documentation Fondations et vocabulaire Information et documentation — Fondations et vocabulaire https://www.iso.org/standard/59743.html https://www.iso.org/obp/ui/en/#!iso:std:59743:en https://www.iso.org/contents/data/standard/05/97/59743.detail.rss ISO 5127:2017 ISO 5127:2017(E) urn:iso:std:iso:5127:stage-90.92 5127 2017-05 International Organization for Standardization ISO www.iso.org committee International Organization for Standardization Information and documentation ISO/TC 46 ISO 2 en fr ISO 5127:2017 provides a concept system and general vocabulary for the field of documentation within the whole information field. It has been created with a balanced representation of major work areas in mind: documentation, libraries, archives, media, museums, records management, conservation as well as legal aspects of documentation. The scope of the vocabulary provided in this document corresponds to that of ISO/TC 46: standardization of practices relating to libraries, documentation and information centres, publishing, archives, records management, museum documentation, indexing and abstracting services, and information science. ISO 5127:2017 provides a concept system and general vocabulary for the field of documentation within the whole information field. It has been created with a balanced representation of major work areas in mind: documentation, libraries, archives, media, museums, records management, conservation as well as legal aspects of documentation. The scope of the vocabulary provided in this document corresponds to that of ISO/TC 46: standardization of practices relating to libraries, documentation and information centres, publishing, archives, records management, museum documentation, indexing and abstracting services, and information science. 90 92 2017 ISO ISO 5127:2001 ISO 5127:2001 ISO/AWI 5127 ISO/AWI 5127 ISO/WD 5127 ISO/WD 5127 Geneva 2026-05-13 Information technology Vocabulary Information technology — Vocabulary Technologies de l’information Vocabulaire Technologies de l’information — Vocabulaire https://www.iso.org/standard/63598.html https://www.iso.org/obp/ui/en/#!iso:std:63598:en https://www.iso.org/contents/data/standard/06/35/63598.detail.rss ISO/IEC 2382:2015 ISO/IEC 2382:2015(E) urn:iso:std:iso-iec:2382:stage-90.93 2382 2015-05 International Organization for Standardization ISO www.iso.org International Electrotechnical Commission IEC www.iec.ch committee International Organization for Standardization Information technology ISO/IEC JTC 1 ISO 1 en fr This standard of vocabulary taken from the multi-part ISO/IEC 2382 standard is presented in language-specific order and is intended to facilitate international communication in information technology. It presents, in two languages, terms and definitions of selected concepts relevant to this field. In order to facilitate their translation into other languages, the definitions are drafted so as to avoid, as far as possible, any peculiarity attached to a language. La présente norme de vocabulaire, qui provient des multiples parties de l’ISO/CEI 2382, est présentée en ordre de tri spécifique de la langue et a pour objet de faciliter les échanges internationaux dans le domaine des technologies de l’information. À cet effet, elle présente un ensemble bilingue de termes et de définitions ayant trait à des notions choisies dans ce domaine. Les définitions ont été établies de manière à éviter les particularismes propres à une langue donnée, en vue de faciliter leur transposition dans les langues autres que celles ayant servi à la rédaction initiale. 90 93 2015 ISO/IEC ISO/IEC 2382-1:1993 ISO/IEC 2382-1:1993 ISO 2382-2:1976 ISO 2382-2:1976 ISO 2382-3:1987 ISO 2382-3:1987 ISO/IEC 2382-4:1999 ISO/IEC 2382-4:1999 ISO/IEC 2382-5:1999 ISO/IEC 2382-5:1999 ISO 2382-6:1987 ISO 2382-6:1987 ISO/IEC 2382-7:2000 ISO/IEC 2382-7:2000 ISO/IEC 2382-8:1998 ISO/IEC 2382-8:1998 ISO/IEC 2382-9:1995 ISO/IEC 2382-9:1995 ISO 2382-10:1979 ISO 2382-10:1979 ISO 2382-12:1988 ISO 2382-12:1988 ISO/IEC 2382-13:1996 ISO/IEC 2382-13:1996 ISO/IEC 2382-14:1997 ISO/IEC 2382-14:1997 ISO/IEC 2382-15:1999 ISO/IEC 2382-15:1999 ISO/IEC 2382-16:1996 ISO/IEC 2382-16:1996 ISO/IEC 2382-17:1999 ISO/IEC 2382-17:1999 ISO/IEC 2382-18:1999 ISO/IEC 2382-18:1999 ISO 2382-19:1989 ISO 2382-19:1989 ISO/IEC 2382-20:1990 ISO/IEC 2382-20:1990 ISO 2382-21:1985 ISO 2382-21:1985 ISO/IEC 2382-23:1994 ISO/IEC 2382-23:1994 ISO/IEC 2382-24:1995 ISO/IEC 2382-24:1995 ISO/IEC 2382-25:1992 ISO/IEC 2382-25:1992 ISO/IEC 2382-26:1993 ISO/IEC 2382-26:1993 ISO/IEC 2382-27:1994 ISO/IEC 2382-27:1994 ISO/IEC 2382-28:1995 ISO/IEC 2382-28:1995 ISO/IEC 2382-29:1999 ISO/IEC 2382-29:1999 ISO/IEC 2382-31:1997 ISO/IEC 2382-31:1997 ISO/IEC 2382-32:1999 ISO/IEC 2382-32:1999 ISO/IEC 2382-34:1999 ISO/IEC 2382-34:1999 ISO/IEC 2382-37:2012 ISO/IEC 2382-37:2012 Geneva UN/ECE Recommendation No. 16, UN/LOCODE: United Nations Code for Ports and other Locations UN/LOCODE en ISO 3166 Maintenance Agency, ISO 3166/MA 3166/MA en Bureau International des Poids et Mesures / The International Bureau of Weights and Measures: The 26th General Conference on Weights and Measures (CGPM), Resolutions adopted, 2018 Resolution 2 of the 26th CGPM (2019) 2 of the 26th CGPM (2019) en Bureau International des Poids et Mesures / The International Bureau of Weights and Measures: The 15th General Conference on Weights and Measures (CGPM), Resolutions adopted, 1975 Resolution 5 of the 15th CGPM (1975) 5 of the 15th CGPM (1975) en Resolutions of Commissions 4 (Ephemerides/Ephemerides) and 31 (Time/L’Heure), XVIth General Assembly, Grenoble, France, IAU, 1976 Resolution 4 by Commissions 4 and 31 at 16th IAU GA 4 by Commissions 4 and 31 at 16th IAU GA en 2026-05-13 Standard-frequency and time-signal emissions https://www.itu.int/dms_pubrec/itu-r/rec/tf/R-REC-TF.460-6-200202-I!!PDF-E.pdf ITU-R TF.460-6 en Standard-frequency and time-signal emissions https://www.itu.int/dms_pubrec/itu-r/rec/tf/R-REC-TF.460-6-200202-I!!PDF-E.pdf ITU-R TF.460-6 2006-02 en