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Note: The following is an excerpt from the official IEC catalog. It is provided here as a convenience and is not authoritative. Refer to the original document as the authoritative reference.

IEC 62541-3:2020 is available as IEC 62541-3:2020 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition. IEC 62541-3:2020 defines the OPC Unified Architecture (OPC UA) AddressSpace and its Objects. This document is the OPC UA meta model on which OPC UA information models are based. This third edition cancels and replaces the second edition published in 2015. This edition includes the following significant technical changes with respect to the previous edition:

a) Added new improved approach for exposing structure definitions. An Attribute on the DataType Node now simply contains a binary description.

b) Added new flags for Variables to indicate atomicity when reading or writing.

c) Added Roles and Permissions to allow configuration of a role-based authorization.

d) Added new data types:

1. Union
2. Decimal
3. OptionSet
4. DateString
5. TimeString
6. DurationString
7. NormalizedString
8. DecimalString
9. AudioDataType

e) Added definition on how to use the

1. ModellingRules
2. OptionalPlaceHolder
3. MandatoryPlaceHolder for Method

f) Added optional Properties

1. MaxCharacters
2. MaxByteStringLength to Variable Nodes

See also:

• IEC 62541-001 OPC Unified Architecture - Part 1: Overview and concepts
• IEC 62541-002 OPC Unified Architecture - Part 2: Security Model
• IEC 62541-003 OPC Unified Architecture - Part 3: Address Space Model
• IEC 62541-004 OPC Unified Architecture - Part 4: Services
• IEC 62541-005 OPC Unified Architecture - Part 5: Information Model
• IEC 62541-006 OPC Unified Architecture - Part 6: Mappings
• IEC 62541-007 OPC Unified Architecture - Part 7: Profiles
• IEC 62541-008 OPC Unified Architecture - Part 8: Data Access
• IEC 62541-009 OPC Unified Architecture - Part 9: Alarms and Conditions
• IEC 62541-010 OPC Unified Architecture - Part 10: Programs
• IEC 62541-011 OPC Unified Architecture - Part 11: Historical Access
• IEC 62541-012 OPC Unified Architecture - Part 12: Discovery and global
• IEC 62541-013 OPC Unified Architecture - Part 13: Aggregates
• IEC 62541-014 OPC Unified Architecture - Part 14: PubSub
• IEC 62541-100 OPC Unified Architecture - Part 100: Device Interface