ISO/IEC 9594-2:2020/Amd 2:2025
(Amendment)Information technology — Open systems interconnection — Part 2: The Directory: Models — Amendment 2: Miscellaneous enhancements
Information technology — Open systems interconnection — Part 2: The Directory: Models — Amendment 2: Miscellaneous enhancements
Technologies de l'information — Interconnexion de systèmes ouverts (OSI) — Partie 2: Titre manque — Amendement 2: Titre manque
General Information
Relations
Standards Content (Sample)
International
Standard
ISO/IEC 9594-2
Ninth edition
Information technology — Open
2020-11
systems interconnection —
AMENDMENT 2
Part 2:
2025-05
The Directory: Models
AMENDMENT 2: Miscellaneous
enhancements
Reference number
ISO/IEC 9594-2:2020/Amd. 2:2025(en) © ISO/IEC 2025
ISO/IEC 9594-2:2020/Amd. 2:2025(en)
© ISO/IEC 2025
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© ISO/IEC 2025 – All rights reserved
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ISO/IEC 9594-2:2020/Amd. 2:2025(en)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
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described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of document should be noted.
ISO and IEC draw attention to the possibility that the implementation of this document may involve the
use of (a) patent(s). ISO and IEC take no position concerning the evidence, validity or applicability of any
claimed patent rights in respect thereof. As of the date of publication of this document, ISO and IEC had
not received notice of (a) patent(s) which may be required to implement this document. However,
implementers are cautioned that this may not represent the latest information, which may be obtained
from the patent database available at www.iso.org/patents and https://patents.iec.ch. ISO and IEC shall
not be held responsible for identifying any or all such patent rights.
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For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT)
see www.iso.org/iso/foreword.html. In the IEC, see www.iec.ch/understanding-standards.
This document was prepared by ITU-T as ITU-T X.501 (2019) Amd. 2 (10/2024) and drafted in
accordance with its editorial rules, in collaboration with Joint Technical Committee ISO/IEC JTC 1,
Information technology, Subcommittee SC 6, Telecommunications and information exchange between
systems.
A list of all parts in the ISO/IEC 9594 series can be found on the ISO and IEC websites.
Any feedback or questions on this document should be directed to the user’s national standards body.
A complete listing of these bodies can be found at www.iso.org/members.html and
www.iec.ch/national-committees.
Rec. ITU-T X.501 (2019) Amd. 2 (10/2024)
© ISO/IEC 2025 – All rights reserved
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ISO/IEC 9594-2:2020/Amd. 2:2025(en)
INTERNATIONAL STANDARD ISO/IEC 9594-2
RECOMMENDATION ITU-T X.501
Information technology – Open Systems Interconnection – The Directory: Models
Amendment 2
Miscellaneous enhancements
Summary
Recommendation ITU-T X.501 (2019) | International Standard ISO/IEC 9594-2:2020, Amendment 2 introduces text
updates to facilitate separation between cybersecurity ASN.1 modules and directory ASN.1 modules.
History
Edition Recommendation Approval Study Group Unique ID
1.0 ITU-T X.501 1988-11-25 11.1002/1000/2997
2.0 ITU-T X.501 1993-11-16 7 11.1002/1000/2998
3.0 ITU-T X.501 1997-08-09 7 11.1002/1000/4122
3.1 ITU-T X.501 (1997) Technical Cor. 1 2000-03-31 7 11.1002/1000/5031
3.2 ITU-T X.501 (1997) Amd. 1 2000-03-31 7 11.1002/1000/5030
3.3 ITU-T X.501 (1997) Technical Cor. 2 2001-02-02 7 11.1002/1000/5308
3.4 ITU-T X.501 (1997) Technical Cor. 3 2005-05-14 17 11.1002/1000/8499
4.0 ITU-T X.501 2001-02-02 7 11.1002/1000/5310
4.1 ITU-T X.501 (2001) Technical Cor. 1 2005-05-14 17 11.1002/1000/8500
4.2 ITU-T X.501 (2001) Technical Cor. 2 2005-11-29 17 11.1002/1000/8634
4.3 ITU-T X.501 (2001) Cor. 3 2008-05-29 17 11.1002/1000/9431
5.0 ITU-T X.501 2005-08-29 17 11.1002/1000/8489
5.1 ITU-T X.501 (2005) Cor. 1 2008-05-29 17 11.1002/1000/9432
5.2 ITU-T X.501 (2005) Cor. 2 2008-11-13 17 11.1002/1000/9589
5.3 ITU-T X.501 (2005) Cor. 3 2011-02-13 17 11.1002/1000/11040
5.4 ITU-T X.501 (2005) Cor. 4 2012-04-13 17 11.1002/1000/11575
6.0 ITU-T X.501 2008-11-13 17 11.1002/1000/9588
6.1 ITU-T X.501 (2008) Cor. 1 2011-02-13 17 11.1002/1000/11041
6.2 ITU-T X.501 (2008) Cor. 2 2012-04-13 17 11.1002/1000/11576
6.3 ITU-T X.501 (2008) Cor. 3 2012-10-14 17 11.1002/1000/11734
7.0 ITU-T X.501 2012-10-14 17 11.1002/1000/11733
8.0 ITU-T X.501 2016-10-14 17 11.1002/1000/13030
9.0 ITU-T X.501 2019-10-14 17 11.1002/1000/14032
9.1 ITU-T X.501 (2019) Amd. 1 2021-10-14 17 11.1002/1000/14790
9.2 ITU-T X.501 (2019) Amd. 2 2024-10-29 17 11.1002/1000/16171
To access the Recommendation, type the URL https://handle.itu.int/ in the address field of your web browser, followed by the
Recommendation's unique ID.
Rec. ITU-T X.501 (2019) Amd. 2 (10/2024)
© ISO/IEC 2025 – All rights reserved
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ISO/IEC 9594-2:2020/Amd. 2:2025(en)
FOREWORD
The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of
telecommunications, and information and communication technologies (ICTs). The ITU Telecommunication
Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical,
operating and tariff questions and issuing Recommendations on them with a view to standardizing
telecommunications on a worldwide basis.
The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes
the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
In some areas of information technology which fall within ITU-T's purview, the necessary standards are
prepared on a collaborative basis with ISO and IEC.
NOTE
In this Recommendation, the expression "Administration" is used for conciseness to indicate both a
telecommunication administration and a recognized operating agency.
Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain
mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the
Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other
obligatory language such as "must" and the negative equivalents are used to express requirements. The use of
such words does not suggest that compliance with the Recommendation is required of any party.
INTELLECTUAL PROPERTY RIGHTS
ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve
the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or
applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of
the Recommendation development process.
As of the date of approval of this Recommendation, ITU had not received notice of intellectual property,
protected by patents/software copyrights, which may be required to implement this Recommendation.
However, implementers are cautioned that this may not represent the latest information and are therefore
strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at
https://www.itu.int/ITU-T/ipr/.
ITU 2025
All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior
written permission of ITU.
Rec. ITU-T X.501 (2019) Amd. 2 (10/2024)
© ISO/IEC 2025 – All rights reserved
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ISO/IEC 9594-2:2020/Amd. 2:2025(en)
CONTENTS
Page
1) Clause 5 . 1
2) Clause 8.2 . 1
3) Clause 8.4 . 1
4) Clause 8.8 . 1
5) Clause 9.2 . 1
6) Clause 9.3 . 1
7) Clause 13.3.3 . 1
8) Clause 13.4.8 . 2
9) Clause 13.5.2 . 2
10) Clause 13.7.3 . 2
11) Clause 13.9.2 . 2
12) Clause 13.12 . 2
13) Annex A . 2
14) Annex B . 14
15) Annex C . 28
16) Annex D . 29
17) Annex E . 30
18) Annex F . 30
19) Annex G . 31
20) Annex H . 32
21) Annex I . 33
Rec. ITU-T X.501 (2019) Amd. 2 (10/2024)
© ISO/IEC 2025 – All rights reserved
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ISO/IEC 9594-2:2020/Amd. 2:2025(en)
INTERNATIONAL STANDARD
ITU-T RECOMMENDATION
Information technology – Open Systems Interconnection – The Directory: Models
Amendment 2
Miscellaneous enhancements
1) Clause 5
Add the following new paragraph at the end of clause 5:
As described in Annex A, some ASN.1 symbols have been moved from the InformationFramework module (Annex B)
to the UsefulDefinitions module (Annex A). However, in the main body of text the locations of the specifications
for these ASN.1 symbols are not changed as they still are logical parts of the information framework as they are present
in the InformationFramework module by being imported from the UsefulDefinitions module.
2) Clause 8.2
In clause 8.2 after the ASN.1 specification for Attribute, add:
NOTE 3 – This parameterized data type was moved from the InformationFramework module to the
UsefulDefinitions module after the ninth edition of this Directory Specification.
3) Clause 8.4
In clause 8.4 after the ASN.1 specification for AttributeType, add:
NOTE – This data type was moved from the InformationFramework module to the UsefulDefinitions module after
the ninth edition of this Directory Specification.
4) Clause 8.8
In clause 8.8 after the ASN.1 specification for Context, add:
NOTE 2 – This data type was moved from the InformationFramework module to the UsefulDefinitions module after
the ninth edition of this Directory Specification.
Renumber other NOTEs in clause 8.8 as required.
5) Clause 9.2
In clause 9.2 after the ASN.1 specification for Name and DomainName, add:
NOTE 2 – The Name and DomainName data types were moved from the InformationFramework module to the
UsefulDefinitions module after the ninth edition of this Directory Specification.
In clause 9.2 after the ASN.1 specification for DistinguishedName, add:
NOTE 4 – The RDNSequence and DistinguishedName data types were moved from the InformationFramework
module to the
...
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