SIST EN IEC 62541-3:2026
(Main)OPC unified architecture - Part 3: Address space model (IEC 62541-3:2025)
OPC unified architecture - Part 3: Address space model (IEC 62541-3:2025)
IEC 62541-3: 2025 describes the OPC Unified Architecture (OPC UA) AddressSpace and its Objects. This specification is the OPC UA meta model on which OPC UA information models are based. This fourth edition cancels and replaces the third edition published in 2020. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) addition of the concept and modelling elements for Interfaces and AddIns;
b) addition of Currency;
c) addition of Method Meta Data to define additional attributes for Method Arguments;
d) addition of ApplyRestrictionToBrowse bit to AccessRestrictionType;
e) addition of a Non-Volatile Storage bit to AccessLevelExType;
f) addition of a Constant bit and ConfigurationConstant bit to AccessLevelExType;
g) the View NodeClass has been changed to define the EventNotifier as an EventNotifierType in the same way the Object NodeClass defines it;
h) correctition of HasNotifier, HasEventSource, and Organizes, to include ObjectType as valid source node;
i) NamingRules have become deprecated;
j) addition of AssociatedWith ReferenceType.
OPC Unified Architecture - Teil 3: Adressraummodell (IEC 62541-3:2025)
Architecture unifiée OPC - Partie 3: Modèle d'espace d'adressage (IEC 62541-3:2025)
IEC 62541-3: 2025 décrit l'AddressSpace de l'Architecture unifiée OPC (OPC UA) et ses Objets. La présente spécification correspond au métamodèle OPC UA sur lequel se fondent les modèles d'information OPC UA. Cette quatrième édition annule et remplace la troisième édition parue en 2020. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) ajout du concept et des éléments de modélisation pour les Interfaces et AddIns;
b) ajout de Currency;
c) ajout des Métadonnées de Méthode afin de définir des attributs supplémentaires pour les Arguments de Méthode;
d) ajout du bit ApplyRestrictionToBrowse à AccessRestrictionType;
e) ajout d'un bit de mémoire rémanente à AccessLevelExType;
f) ajout d'un bit Constant et d'un bit ConfigurationConstant à AccessLevelExType;
g) modification de la NodeClass View pour définir l'EventNotifier comme un EventNotifierType de la même manière que la NodeClass Object le définit;
h) correction de HasNotifier, HasEventSource et Organizes afin d'inclure ObjectType comme nœud source valide;
i) dépréciation de NamingRules;
j) ajout du ReferenceType AssociatedWith.
Enotna arhitektura OPC - 3. del: Model naslovnega prostora (IEC 62541-3:2025)
IEC 62541-3: 2025 opisuje naslovni prostor (AddressSpace) in njegove objekte v okviru enotne arhitekture OPC (OPC UA). Ta specifikacija je OPC UA meta model, na katerem temeljijo informacijski modeli OPC UA. Ta četrta izdaja preklicuje in nadomešča tretjo izdajo, objavljeno leta 2020. Ta izdaja predstavlja tehnično revizijo.
Ta izdaja vključuje naslednje pomembne tehnične spremembe v primerjavi s prejšnjo izdajo:
a) dodajanje koncepta in modelirnih elementov za vmesnike (Interfaces) in dodatke (AddIns);
b) dodajanje valute (Currency);
c) dodajanje meta podatkov metode (Method Meta Data) za določitev dodatnih atributov za argumente metode;
d) dodajanje bita ApplyRestrictionToBrowse k tipu omejitve dostopa (AccessRestrictionType);
e) dodajanje bita za nehlapno shranjevanje (Non-Volatile Storage) k tipu razširjenega nivoja dostopa (AccessLevelExType);
f) dodajanje bita za konstanto (Constant bit) in bita za konfiguracijsko konstanto (ConfigurationConstant bit) k tipu razširjenega nivoja dostopa (AccessLevelExType);
g) razred vozlišča pogleda (View NodeClass) je bil spremenjen, da definira obveščevalca dogodkov (EventNotifier) kot tip obveščevalca dogodkov (EventNotifierType) na enak način, kot ga definira razred vozlišča objekta (Object NodeClass);
h) popravek HasNotifier, HasEventSource in Organizes, da vključujejo ObjectType kot veljavno izvorno vozlišče;
i) pravila poimenovanja (NamingRules) so postala zastarela;
j) dodajanje referenčnega tipa AssociatedWith.
General Information
- Status
- Published
- Public Enquiry End Date
- 21-Apr-2024
- Publication Date
- 09-Apr-2026
- Technical Committee
- MOV - Measuring equipment for electromagnetic quantities
- Current Stage
- 6060 - National Implementation/Publication (Adopted Project)
- Start Date
- 24-Feb-2026
- Due Date
- 01-May-2026
- Completion Date
- 10-Apr-2026
Relations
- Effective Date
- 20-Feb-2026
- Effective Date
- 20-Feb-2026
- Effective Date
- 10-Feb-2026
- Effective Date
- 10-Feb-2026
- Effective Date
- 10-Feb-2026
- Referred By
SIST EN IEC 62769-1:2021 - Field device integration (FDI) - Part 1: Overview (IEC 62769-1:2021) - Effective Date
- 20-Feb-2026
- Referred By
SIST EN 62541-13:2015 - OPC Unified Architecture -- Part 13: Aggregates (IEC 62541-13:2015) - Effective Date
- 20-Feb-2026
- Effective Date
- 20-Feb-2026
- Effective Date
- 20-Feb-2026
- Effective Date
- 20-Feb-2026
- Effective Date
- 20-Feb-2026
- Referred By
SIST EN IEC 62769-1:2023 - Field Device Integration (FDI®) - Part 1: Overview (IEC 62769-1:2023) - Effective Date
- 20-Feb-2026
- Effective Date
- 20-Feb-2026
- Referred By
SIST EN IEC 62541-4:2020 - OPC Unified Architecture - Part 4: Services (IEC 62541-4:2020) - Effective Date
- 20-Feb-2026
- Effective Date
- 20-Feb-2026
Overview
The oSIST prEN IEC 62541-3:2024 standard, developed by CLC, is the fourth edition of the OPC Unified Architecture (OPC UA) Part 3 specification, titled "Address Space Model." This document defines the OPC UA AddressSpace and its core Objects, providing the foundational meta model upon which OPC UA information models are built. As a technical revision of the 2020 third edition, this updated standard introduces key enhancements to improve interoperability, security, and information modelling for industrial automation and IT applications.
Targeted primarily at professionals in industrial process measurement and control as well as IT applications in industry, oSIST prEN IEC 62541-3:2024 supports robust, flexible, and scalable OPC UA implementations.
Key Topics
This edition introduces several significant updates and extensions to the OPC UA Address Space Model, including:
- Interfaces and AddIns: New concepts and modelling elements are added to support interface and AddIn models, enhancing modularity and reusability of object definitions.
- Currency Attribute: Enables better representation of monetary values within data variables.
- Method Meta Data: Enhanced definition of additional attributes for method arguments to improve method invocation clarity.
- Access Restrictions and Levels: Introduction of new bits such as ApplyRestrictionToBrowse, Non-Volatile Storage, Constant, and ConfigurationConstant to refine access control policies.
- EventNotifierType Standardization: The View NodeClass now defines its EventNotifier as an EventNotifierType, aligning it with the Object NodeClass for consistency.
- Expanded Valid Source Nodes: Adjustments to reference types like HasNotifier, HasEventSource, and Organizes to include ObjectType as valid sources.
- Deprecation of NamingRules: The standard phases out the NamingRules concept to simplify node naming conventions.
- AssociatedWith ReferenceType: Introduction of a new ReferenceType to improve relationships modelling between nodes.
The standard comprehensively covers the AddressSpace’s structural elements such as NodeClasses, Attributes, References, Variables, DataTypes, and Methods. It also delves into the type model for ObjectTypes and VariableTypes, referencing standard ReferenceTypes and DataTypes essential for consistent industrial information modelling.
Applications
oSIST prEN IEC 62541-3:2024 serves as a cornerstone for OPC UA-based implementation in numerous industrial and IT sectors. Typical applications include:
- Industrial Automation Systems: Facilitating semantic interoperability between devices, controllers, and SCADA systems by providing a common information model.
- Process Control and Measurement: Addressing complex addressing and data modelling needs in process instrumentation and control devices.
- IT-Industry Integration: Supporting application solutions requiring seamless information exchange between industrial hardware and enterprise IT systems.
- Security and Access Control: Helping implement granular permission models and access restrictions fundamental for critical system protection.
- Event Management and Method Invocation: Streamlining event categorization and method execution in distributed control and monitoring architectures.
This standard empowers manufacturers, system integrators, and software developers to build interoperable and extensible OPC UA applications that enhance operational efficiency and reliability across industrial environments.
Related Standards
To fully leverage the OPC UA Address Space Model, it is essential to consider the broader IEC 62541 series:
- IEC 62541-1: Overview and Concepts - Provides the general framework and principles underpinning the OPC UA architecture.
- IEC 62541-4: Services - Defines the service interface and communication mechanisms.
- IEC 62541-5: Information Model - Extends the base meta model with additional information model constructs.
- IEC 62541-7: Profiles - Specifies compliance profiles for interoperability.
- IEC 62541-8: Data Access - Focuses on standardizing data access and monitoring.
Integrating oSIST prEN IEC 62541-3:2024 with these standards ensures comprehensive adoption of OPC UA technologies, advancing standardized communication and information modelling for smart manufacturing and Industry 4.0 initiatives.
By implementing the updated OPC UA Address Space Model as defined in oSIST prEN IEC 62541-3:2024, organizations can achieve improved device interoperability, consistent data modelling, and enhanced security management-critical components for modern industrial automation and IT application success.
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Frequently Asked Questions
SIST EN IEC 62541-3:2026 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "OPC unified architecture - Part 3: Address space model (IEC 62541-3:2025)". This standard covers: IEC 62541-3: 2025 describes the OPC Unified Architecture (OPC UA) AddressSpace and its Objects. This specification is the OPC UA meta model on which OPC UA information models are based. This fourth edition cancels and replaces the third edition published in 2020. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) addition of the concept and modelling elements for Interfaces and AddIns; b) addition of Currency; c) addition of Method Meta Data to define additional attributes for Method Arguments; d) addition of ApplyRestrictionToBrowse bit to AccessRestrictionType; e) addition of a Non-Volatile Storage bit to AccessLevelExType; f) addition of a Constant bit and ConfigurationConstant bit to AccessLevelExType; g) the View NodeClass has been changed to define the EventNotifier as an EventNotifierType in the same way the Object NodeClass defines it; h) correctition of HasNotifier, HasEventSource, and Organizes, to include ObjectType as valid source node; i) NamingRules have become deprecated; j) addition of AssociatedWith ReferenceType.
IEC 62541-3: 2025 describes the OPC Unified Architecture (OPC UA) AddressSpace and its Objects. This specification is the OPC UA meta model on which OPC UA information models are based. This fourth edition cancels and replaces the third edition published in 2020. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) addition of the concept and modelling elements for Interfaces and AddIns; b) addition of Currency; c) addition of Method Meta Data to define additional attributes for Method Arguments; d) addition of ApplyRestrictionToBrowse bit to AccessRestrictionType; e) addition of a Non-Volatile Storage bit to AccessLevelExType; f) addition of a Constant bit and ConfigurationConstant bit to AccessLevelExType; g) the View NodeClass has been changed to define the EventNotifier as an EventNotifierType in the same way the Object NodeClass defines it; h) correctition of HasNotifier, HasEventSource, and Organizes, to include ObjectType as valid source node; i) NamingRules have become deprecated; j) addition of AssociatedWith ReferenceType.
SIST EN IEC 62541-3:2026 is classified under the following ICS (International Classification for Standards) categories: 25.040.40 - Industrial process measurement and control; 35.100.05 - Multilayer applications; 35.240.50 - IT applications in industry. The ICS classification helps identify the subject area and facilitates finding related standards.
SIST EN IEC 62541-3:2026 has the following relationships with other standards: It is inter standard links to SIST ISO 639:2024, SIST EN IEC 62541-11:2026, SIST EN IEC 62541-8:2020, SIST EN IEC 62541-18:2025, SIST EN IEC 62541-1:2026, SIST EN IEC 62769-1:2021, SIST EN 62541-13:2015, SIST EN 62541-6:2012, SIST EN 62769-3:2015, SIST EN IEC 62769-7:2021, SIST EN IEC 62769-5:2021, SIST EN IEC 62769-1:2023, SIST EN IEC 62769-8:2023, SIST EN IEC 62541-4:2020, SIST EN 62541-4:2012. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
SIST EN IEC 62541-3:2026 is associated with the following European legislation: Standardization Mandates: M/490. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.
SIST EN IEC 62541-3:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-maj-2026
Enotna arhitektura OPC - 3. del: Model naslovnega prostora (IEC 62541-3:2025)
OPC unified architecture - Part 3: Address space model (IEC 62541-3:2025)
OPC Unified Architecture - Teil 3: Adressraummodell (IEC 62541-3:2025)
Architecture unifiée OPC - Partie 3: Modèle d'espace d'adressage (IEC 62541-3:2025)
Ta slovenski standard je istoveten z: EN IEC 62541-3:2026
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
35.240.50 Uporabniške rešitve IT v IT applications in industry
industriji
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN IEC 62541-3
NORME EUROPÉENNE
EUROPÄISCHE NORM February 2026
ICS 25.040.40; 35.100.05 Supersedes EN IEC 62541-3:2020
English Version
OPC unified architecture - Part 3: Address Space Model
(IEC 62541-3:2025)
Architecture unifiée OPC - Partie 3: Modèle d'espace OPC Unified Architecture - Teil 3: Adressraummodell
d'adressage (IEC 62541-3:2025)
(IEC 62541-3:2025)
This European Standard was approved by CENELEC on 2026-01-26. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 62541-3:2026 E
European foreword
The text of document 65E/1061/CDV, future edition 4 of IEC 62541-3, prepared by SC 65E "Devices
and integration in enterprise systems" of IEC/TC 65 "Industrial-process measurement, control and
automation" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2027-02-28
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2029-02-28
document have to be withdrawn
This document supersedes EN IEC 62541-3:2020 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a standardization request addressed to CENELEC by the
European Commission. The Standing Committee of the EFTA States subsequently approves these
requests for its Member States.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 62541-3:2025 was approved by CENELEC as a European
Standard without any modification.
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 62541-1 - OPC Unified Architecture - Part 1: EN IEC 62541-1 -
Overview and concepts
IEC 62541-4 - OPC unified architecture - Part 4: Services EN IEC 62541-4 -
IEC 62541-5 - OPC Unified architecture - Part 5: EN IEC 62541-5 -
Information Model
IEC 62541-6 - OPC unified architecture - Part 6: EN IEC 62541-6 -
Mappings
IEC 62541-8 - OPC unified architecture - Part 8: Data EN IEC 62541-8 -
access
IEC 62541-11 - OPC Unified Architecture - Part 11: EN IEC 62541-11 -
Historical Access
IEC 62541-18 - OPC unified architecture - Part 18: Role- EN IEC 62541-18 -
Based Security
IEC 62541-21 - OPC Unified architecture - Part 21: Device EN IEC 62541-21 -
Onboarding
ISO 639 series Code for individual languages and - -
language groups
ISO 3166 series Country codes - -
ISO 4217 - Codes for the representation of currencies - -
ISO 8601-1 2019 Date and time - Representations for - -
information interchange - Part 1: Basic
rules
ISO/IEC/IEEE 2020 Information technology - Microprocessor - -
60559 Systems - Floating-Point arithmetic
IETF RFC 3986 - Uniform Resource Identifier (URI): Generic - -
Syntax
IETF RFC 4151 - The 'tag' URI Scheme - -
IETF RFC 5646 - Tags for Identifying Languages - -
Unicode Annex 15 - Unicode Standard Annex #15: Unicode - -
Normalization Forms
- W3C XML Schema Definition Language - -
(XSD) Part 2, DataTypes
- Unicode C0 Controls and Basic Latin - -
- Unicode C1 Controls and Latin-1 - -
Supplement
IEC 62541-3 ®
Edition 4.0 2025-12
INTERNATIONAL
STANDARD
OPC unified architecture -
Part 3: Address Space Model
ICS 25.040.40; 35.100.05 ISBN 978-2-8327-0839-2
IEC 62541-3:2025-12(en)
IEC 62541-3:2025 © IEC 2025
CONTENTS
FOREWORD . 10
1 Scope . 12
2 Normative references . 12
3 Terms, definitions, abbreviations and conventions . 13
3.1 Terms and definitions. 13
3.2 Abbreviated terms . 14
3.3 Conventions . 14
3.3.1 Conventions for AddressSpace figures . 14
3.3.2 Conventions for defining NodeClasses . 15
4 AddressSpace concepts . 16
4.1 Overview . 16
4.2 URIs . 17
4.3 Object Model . 18
4.4 Node Model . 18
4.4.1 General . 18
4.4.2 NodeClasses . 19
4.4.3 Attributes . 19
4.4.4 References . 19
4.5 Variables . 20
4.5.1 General . 20
4.5.2 Properties . 20
4.5.3 DataVariables . 20
4.6 TypeDefinitionNodes . 21
4.6.1 General . 21
4.6.2 Complex TypeDefinitionNodes and their InstanceDeclarations . 21
4.6.3 Subtyping . 22
4.6.4 Instantiation of complex TypeDefinitionNodes . 23
4.7 Event Model . 24
4.7.1 General . 24
4.7.2 EventTypes . 24
4.7.3 Event Categorization . 25
4.8 Methods . 25
4.9 Roles . 25
4.9.1 Overview . 25
4.9.2 Well Known Roles. 26
4.9.3 Evaluating Permissions with Roles . 27
4.10 Interfaces and AddIns for Objects . 29
4.10.1 Overview . 29
4.10.2 Interface Model . 29
4.10.3 AddIn model . 33
5 Standard NodeClasses . 34
5.1 Overview . 34
5.2 Base NodeClass . 35
5.2.1 General . 35
5.2.2 NodeId . 35
5.2.3 NodeClass . 35
IEC 62541-3:2025 © IEC 2025
5.2.4 BrowseName . 35
5.2.5 DisplayName . 36
5.2.6 Description . 36
5.2.7 WriteMask . 36
5.2.8 UserWriteMask . 36
5.2.9 RolePermissions . 37
5.2.10 UserRolePermissions . 38
5.2.11 AccessRestrictions . 38
5.3 ReferenceType NodeClass . 38
5.3.1 General . 38
5.3.2 Attributes . 39
5.3.3 References . 41
5.4 View NodeClass . 41
5.5 Objects . 43
5.5.1 Object NodeClass . 43
5.5.2 ObjectType NodeClass . 44
5.5.3 Standard ObjectType FolderType . 46
5.5.4 Client-side creation of Objects of an ObjectType . 46
5.6 Variables . 47
5.6.1 General . 47
5.6.2 Variable NodeClass . 47
5.6.3 Properties . 51
5.6.4 DataVariable. 52
5.6.5 VariableType NodeClass . 53
5.6.6 Client-side creation of Variables of an VariableType . 55
5.7 Methods . 55
5.7.1 Method NodeClass . 55
5.7.2 HasArgumentDescription ReferenceType. 59
5.7.3 HasOptionalInputArgumentDescription ReferenceType . 59
5.8 DataTypes . 59
5.8.1 DataType Model . 59
5.8.2 Encoding Rules for different kinds of DataTypes . 60
5.8.3 DataType NodeClass . 61
5.8.4 DataTypeEncoding and Encoding Information . 64
5.9 Summary of Attributes of the NodeClasses . 64
6 Type Model for ObjectTypes and VariableTypes . 65
6.1 Overview . 65
6.2 Definitions . 66
6.2.1 InstanceDeclaration . 66
6.2.2 Instances without ModellingRules . 66
6.2.3 InstanceDeclarationHierarchy . 66
6.2.4 Similar Node of InstanceDeclaration . 66
6.2.5 BrowsePath . 66
6.2.6 BrowseName within a TypeDefinitionNode . 66
6.2.7 Attribute Handling of InstanceDeclarations . 66
6.2.8 Attribute Handling of Variable and VariableTypes . 67
6.2.9 NodeIds of InstanceDeclarations . 67
6.3 Subtyping of ObjectTypes and VariableTypes . 67
6.3.1 Overview . 67
IEC 62541-3:2025 © IEC 2025
6.3.2 Attributes . 67
6.3.3 InstanceDeclarations . 67
6.4 Instances of ObjectTypes and VariableTypes . 72
6.4.1 Overview . 72
6.4.2 Creating an Instance . 72
6.4.3 Constraints on an Instance . 73
6.4.4 ModellingRules . 74
6.5 Changing Type Definitions that are already used . 82
7 Standard ReferenceTypes . 83
7.1 General . 83
7.2 References ReferenceType . 83
7.3 HierarchicalReferences ReferenceType . 84
7.4 NonHierarchicalReferences ReferenceType . 84
7.5 HasChild ReferenceType . 84
7.6 Aggregates ReferenceType . 84
7.7 HasComponent ReferenceType . 85
7.8 HasProperty ReferenceType . 85
7.9 HasOrderedComponent ReferenceType . 85
7.10 HasSubtype ReferenceType. 85
7.11 Organizes ReferenceType . 86
7.12 HasModellingRule ReferenceType . 86
7.13 HasTypeDefinition ReferenceType . 86
7.14 HasEncoding ReferenceType . 86
7.15 GeneratesEvent . 87
7.16 AlwaysGeneratesEvent . 87
7.17 HasEventSource . 87
7.18 HasNotifier . 88
7.19 HasInterface ReferenceType . 89
7.20 HasAddIn ReferenceType . 89
7.21 IsDeprecated ReferenceType . 90
7.22 HasStructuredComponent ReferenceType . 90
7.22.1 Overview . 90
7.22.2 Differences between HasStructuredComponent and ExposesItsArray . 91
7.23 AssociatedWith ReferenceType . 92
8 Standard DataTypes . 92
8.1 General . 92
8.2 NodeId . 92
8.2.1 General . 92
8.2.2 NamespaceIndex . 93
8.2.3 IdType . 93
8.2.4 Identifier value . 94
8.3 QualifiedName . 94
8.4 LocaleId . 94
8.5 LocalizedText . 95
8.6 Argument . 95
8.7 BaseDataType . 96
8.8 Boolean . 96
8.9 Byte . 96
8.10 ByteString . 96
IEC 62541-3:2025 © IEC 2025
8.11 DateTime . 97
8.12 Double . 97
8.13 Duration . 97
8.14 Enumeration . 97
8.15 Float . 97
8.16 Guid . 97
8.17 Sbyte . 97
8.18 IdType . 97
8.19 Image . 97
8.20 ImageBMP . 97
8.21 ImageGIF . 98
8.22 ImageJPG . 98
8.23 ImagePNG . 98
8.24 Integer . 98
8.25 Int16 . 98
8.26 Int32 . 98
8.27 Int64 . 98
8.28 TimeZoneDataType . 98
8.29 NodeClass . 98
8.30 Number . 99
8.31 String . 99
8.32 Structure . 99
8.33 Uinteger . 99
8.34 Uint16 . 99
8.35 Uint32 . 99
8.36 Uint64 . 99
8.37 UtcTime . 100
8.38 XmlElement . 100
8.39 EnumValueType. 100
8.40 OptionSet . 100
8.41 Union . 101
8.42 DateString . 102
8.43 DecimalString . 102
8.44 DurationString . 102
8.45 NormalizedString . 102
8.46 TimeString . 103
8.47 DataTypeDefinition . 103
8.48 StructureDefinition . 103
8.49 StructureType . 104
8.50 EnumDefinition . 104
8.51 StructureField . 104
8.52 EnumField . 105
8.53 AudioDataType . 106
8.54 Decimal . 106
8.55 PermissionType . 106
8.56 AccessRestrictionType . 107
8.57 AccessLevelType . 108
8.58 AccessLevelExType . 108
8.59 EventNotifierType . 110
IEC 62541-3:2025 © IEC 2025
8.60 AttributeWriteMask . 110
8.61 CurrencyUnitType . 111
9 Standard EventTypes . 112
9.1 General . 112
9.2 BaseEventType . 113
9.3 SystemEventType . 113
9.4 ProgressEventType. 113
9.5 AuditEventType . 114
9.6 AuditSecurityEventType . 115
9.7 AuditChannelEventType . 115
9.8 AuditOpenSecureChannelEventType . 115
9.9 AuditSessionEventType . 115
9.10 AuditCreateSessionEventType . 116
9.11 AuditUrlMismatchEventType . 116
9.12 AuditActivateSessionEventType . 116
9.13 AuditCancelEventType . 116
9.14 AuditCertificateEventType . 116
9.15 AuditCertificateDataMismatchEventType . 116
9.16 AuditCertificateExpiredEventType . 116
9.17 AuditCertificateInvalidEventType . 116
9.18 AuditCertificateUntrustedEventType . 116
9.19 AuditCertificateRevokedEventType . 117
9.20 AuditCertificateMismatchEventType . 117
9.21 AuditNodeManagementEventType . 117
9.22 AuditAddNodesEventType . 117
9.23 AuditDeleteNodesEventType. 117
9.24 AuditAddReferencesEventType . 117
9.25 AuditDeleteReferencesEventType . 117
9.26 AuditUpdateEventType . 117
9.27 AuditWriteUpdateEventType . 117
9.28 AuditHistoryUpdateEventType . 117
9.29 AuditUpdateMethodEventType . 117
9.30 DeviceFailureEventType . 118
9.31 SystemStatusChangeEventType . 118
9.32 ModelChangeEvents . 118
9.32.1 General . 118
9.32.2 NodeVersion Property . 118
9.32.3 Views . 118
9.32.4 Event compression . 118
9.32.5 BaseModelChangeEventType . 119
9.32.6 GeneralModelChangeEventType . 119
9.32.7 Guidelines for ModelChangeEvents . 119
9.33 SemanticChangeEventType . 119
9.33.1 General . 119
9.33.2 ViewVersion and NodeVersion Properties . 119
9.33.3 Views . 120
9.33.4 Event compression . 120
Annex A (informative) How to use the Address Space Model . 121
A.1 Overview . 121
IEC 62541-3:2025 © IEC 2025
A.2 Type definitions . 121
A.3 ObjectTypes . 121
A.4 VariableTypes . 122
A.4.1 General . 122
A.4.2 Properties or DataVariables . 122
A.4.3 Many Variables and / or Structured DataTypes . 122
A.5 Views . 123
A.6 Methods . 123
A.7 Defining ReferenceTypes . 123
A.8 Defining ModellingRules . 123
Annex B (informative) OPC UA Meta Model in UML . 124
B.1 Background . 124
B.2 Notation . 124
B.3 Meta Model . 125
B.3.1 Base . 125
B.3.2 ReferenceType . 126
B.3.3 Predefined ReferenceTypes . 127
B.3.4 Attributes . 127
B.3.5 Object and ObjectType . 128
B.3.6 EventNotifier . 129
B.3.7 Variable and VariableType . 129
B.3.8 Method . 130
B.3.9 DataType . 131
B.3.10 View . 132
Annex C (normative) Graphical notation . 133
C.1 General . 133
C.2 Notation . 133
C.2.1 Overview . 133
C.2.2 Simple notation . 133
C.2.3 Extended notation . 135
Bibliography . 138
Figure 1 – AddressSpace Node diagrams . 15
Figure 2 – OPC UA Object Model . 18
Figure 3 – AddressSpace Node Model . 19
Figure 4 – Reference Model . 20
Figure 5 – Example of a Variable defined by a VariableType . 21
Figure 6 – Example of a Complex TypeDefinition . 22
Figure 7 – Object and its Components defined by an ObjectType . 23
Figure 8 – Examples of Interfaces . 31
Figure 9 – Example: Interface application to an ObjectType . 31
Figure 10 – Example: One Interface applied to an ObjectType another one to the
instance . 32
Figure 11 – Example: Interface Hierarchy . 32
Figure 12 – Example of AddIn with default BrowseName . 33
Figure 13 – Example of AddIn applied to an instance . 34
Figure 14 – Permissions in the Address Space . 38
IEC 62541-3:2025 © IEC 2025
Figure 15 – Symmetric and Non-Symmetric References . 40
Figure 16 – Method Metadata Example . 58
Figure 17 – Variables, VariableTypes and their DataTypes . 59
Figure 18 – DataType Model . 60
Figure 19 – Example of DataType Modelling . 64
Figure 20 – Subtyping TypeDefinitionNodes. 68
Figure 21 – The Fully-Inherited InstanceDeclarationHierarchy for BetaType . 71
Figure 22 – An Instance and its TypeDefinitionNode . 72
Figure 23 – Example for several References between InstanceDeclarations . 74
Figure 24 – Example on changing instances based on InstanceDeclarations . 75
Figure 25 – Example on changing InstanceDeclarations based on an
InstanceDeclaration . 76
Figure 26 – Use of the Standard ModellingRule Mandatory . 77
Figure 27 – Example using the Standard ModellingRules Optional and Mandatory . 78
Figure 28 – Example on using ExposesItsArray . 79
Figure 29 – Complex example on using ExposesItsArray . 79
Figure 30 – Example using OptionalPlaceholder with an Object and Variable . 80
Figure 31 – Example using OptionalPlaceholder with a Method. 81
Figure 32 – Example on using MandatoryPlaceholder for Object and Variable . 82
Figure 33 – Standard ReferenceType Hierarchy . 83
Figure 34 – Event Reference Example .
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