====== IEC 62541-003 OPC Unified Architecture - Part 3: Address Space Model ======
[[dido:public:ra:xapend:xapend.b_stds:tech:iec:start| return to the IEC Standards ]]

<table>
<caption>Data sheet for OPC Unified Architecture - Part 3: Address Space Model</caption>
| Title                      | OPC Unified Architecture - Part 3: Address Space Model |
| Version                    | 2020|
| Document Number            | 62541-3|
| Release Date               | 2020  |
| Reference                  | [[https://webstore.iec.ch/publication/61112]] |
</table>

  : **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.

===== Abstract =====

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: 
    - **''Union''**
    - **''Decimal''**
    - **''OptionSet''**
    - **''DateString''**
    - **''TimeString''**
    - **''DurationString''**
    - **''NormalizedString''**
    - **''DecimalString''** 
    - **''AudioDataType''**
  : e) Added definition on how to use the 
    - **''ModellingRules''**
    - **''OptionalPlaceHolder''** 
    - **''MandatoryPlaceHolder''** for Method
  : f) Added optional Properties 
    - **''MaxCharacters''**
    - **''MaxByteStringLength''** to Variable Nodes

See also:

  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-1]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-2]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-3]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-4]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-5]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-6]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-7]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-8]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-9]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-10]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-11]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-12]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-13]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-14]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-100]]

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