OPC Unified Architecture - Part 8: Data Access (IEC 62541-8:2020)

This part of IEC 62541 is part of the overall OPC Unified Architecture (OPC UA) standard series
and defines the information model associated with Data Access (DA). It particularly includes
additional VariableTypes and complementary descriptions of the NodeClasses and Attributes
needed for Data Access, additional Properties, and other information and behaviour.
The complete address space model, including all NodeClasses and Attributes is specified in
IEC 62541-3. The services to detect and access data are specified in IEC 62541-4.

OPC Unified Architecture - Teil 8: Zugriff auf Automatisierungsdaten (IEC 62541-8:2020)

Architecture unifiée OPC - Partie 8: Accès aux données (IEC 62541-8:2020)

IEC 62541-8:2020 est disponible sous forme de IEC 62541-8:2020 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.L'IEC 62541-8:2020 fait partie intégrante de la série de normes générales sur l'architecture unifiée OPC (OPC UA). Elle définit le modèle d'information associé à l'Accès aux données (DA). Elle spécifie notamment des VariableTypes supplémentaires et fournit des descriptions complémentaires concernant les NodeClasses et attributs nécessaires pour l'Accès aux données, ainsi que des propriétés supplémentaires et d'autres paramètres relatifs aux informations et au comportement. Le modèle d'espace d'adresses complet, comprenant toutes les NodeClasses et tous les Attributs, est spécifié dans l'IEC 62541-3. Les services de détection et d'accès aux données sont spécifiés dans l'IEC 62541-4. Cette troisième édition annule et remplace la deuxième édition parue en 2015. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: a) ajout de nouveaux VariableTypes pour les AnalogItems; b) ajout d'une annexe qui spécifie le mapping recommandé entre OPC UA DataAccess et OPC COM DataAccess; c) modification de la description ambiguë de "Bad_NotConnected"; d) mise à jour de la description de EUInformation pour renvoyer à la dernière révision des unités CEFACT-ONU.

Enotna arhitektura OPC - 8. del: Dostop do podatkov (IEC 62541-8:2020)

General Information

Status
Published
Public Enquiry End Date
08-Nov-2018
Publication Date
05-Nov-2020
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
24-Aug-2020
Due Date
29-Oct-2020
Completion Date
06-Nov-2020

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SLOVENSKI STANDARD
SIST EN IEC 62541-8:2020
01-december-2020
Nadomešča:
SIST EN 62541-8:2015
Enotna arhitektura OPC - 8. del: Dostop do podatkov (IEC 62541-8:2020)
OPC Unified Architecture - Part 8: Data Access (IEC 62541-8:2020)

OPC Unified Architecture - Teil 8: Zugriff auf Automatisierungsdaten (IEC 62541-8:2020)

Architecture unifiée OPC - Partie 8: Accès aux données (IEC 62541-8:2020)
Ta slovenski standard je istoveten z: EN IEC 62541-8:2020
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
SIST EN IEC 62541-8:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN IEC 62541-8:2020
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SIST EN IEC 62541-8:2020
EUROPEAN STANDARD EN IEC 62541-8
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2020
ICS 35.100.05; 25.040.40 Supersedes EN 62541-8:2015 and all of its amendments
and corrigenda (if any)
English Version
OPC Unified Architecture - Part 8: Data Access
(IEC 62541-8:2020)

Architecture unifiée OPC - Partie 8: Accès aux données OPC Unified Architecture - Teil 8: Zugriff auf

(IEC 62541-8:2020) Automatisierungsdaten
(IEC 62541-8:2020)

This European Standard was approved by CENELEC on 2020-07-27. 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,

Turkey 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

© 2020 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN IEC 62541-8:2020 E
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SIST EN IEC 62541-8:2020
EN IEC 62541-8:2020 (E)
European foreword

The text of document 65E/708/FDIS, future edition 3 of IEC 62541-8, 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

EN IEC 62541-8:2020.
The following dates are fixed:

• latest date by which the document has to be implemented at national (dop) 2021-04-27

level by publication of an identical national standard or by endorsement

• latest date by which the national standards conflicting with the (dow) 2023-07-27

document have to be withdrawn

This document supersedes EN 62541-8:2015 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 mandate given to CENELEC by the European Commission

and the European Free Trade Association.
Endorsement notice

The text of the International Standard IEC 62541-8:2020 was approved by CENELEC as a European

Standard without any modification.
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SIST EN IEC 62541-8:2020
EN IEC 62541-8:2020 (E)
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.cenelec.eu.
Publication Year Title EN/HD Year
IEC/TR 62541-1 - OPC unified architecture - Part 1: CLC/TR 62541-1 -
Overview and concepts
IEC 62541-3 - OPC Unified Architecture - Part 3: - -
Address Space Model
IEC 62541-4 - OPC Unified Architecture - Part 4: - -
Services
IEC 62541-5 - OPC Unified Architecture - Part 5: - -
Information Model
UNECE 20 - Codes for Units of Measure Used in - -
International Trade
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SIST EN IEC 62541-8:2020
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SIST EN IEC 62541-8:2020
IEC 62541-8
Edition 3.0 2020-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
OPC unified architecture –
Part 8: Data access
Architecture unifiée OPC –
Partie 8: Accès aux données
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 25.040.40; 35.100.05 ISBN 978-2-8322-8464-3

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
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SIST EN IEC 62541-8:2020
– 2 – IEC 62541-8:2020 © IEC 2020
CONTENTS

FOREWORD ........................................................................................................................... 5

1 Scope .............................................................................................................................. 7

2 Normative references ...................................................................................................... 7

3 Terms, definitions and abbreviated terms ........................................................................ 7

3.1 Terms and definitions .............................................................................................. 7

3.2 Abbreviated terms ................................................................................................... 8

4 Concepts ......................................................................................................................... 8

5 Model .............................................................................................................................. 9

5.1 General ................................................................................................................... 9

5.2 SemanticsChanged ............................................................................................... 10

5.3 Variable Types ...................................................................................................... 10

5.3.1 DataItemType ................................................................................................ 10

5.3.2 AnalogItem VariableTypes ............................................................................. 11

5.3.3 DiscreteItemType .......................................................................................... 14

5.3.4 ArrayItemType ............................................................................................... 17

5.4 Address Space model ........................................................................................... 23

5.5 Attributes of DataItems ......................................................................................... 24

5.6 DataTypes ............................................................................................................ 25

5.6.1 Overview ....................................................................................................... 25

5.6.2 Range ............................................................................................................ 25

5.6.3 EUInformation ............................................................................................... 25

5.6.4 ComplexNumberType .................................................................................... 27

5.6.5 DoubleComplexNumberType ......................................................................... 27

5.6.6 AxisInformation .............................................................................................. 28

5.6.7 AxisScaleEnumeration ................................................................................... 28

5.6.8 XVType ......................................................................................................... 29

6 Data Access specific usage of Services ......................................................................... 29

6.1 General ................................................................................................................. 29

6.2 PercentDeadband ................................................................................................. 29

6.3 Data Access status codes ..................................................................................... 30

6.3.1 Overview ....................................................................................................... 30

6.3.2 Operation level result codes .......................................................................... 30

6.3.3 LimitBits ........................................................................................................ 32

Annex A (informative) OPC COM DA to UA mapping ........................................................... 33

A.1 Overview............................................................................................................... 33

A.2 Security considerations ......................................................................................... 33

A.3 COM UA wrapper for OPC DA Server ................................................................... 33

A.3.1 Information Model mapping ............................................................................ 33

A.3.2 Data and error mapping ................................................................................. 37

A.3.3 Read data ...................................................................................................... 40

A.3.4 Write Data ..................................................................................................... 41

A.3.5 Subscriptions ................................................................................................. 42

A.4 COM UA proxy for DA Client ................................................................................. 42

A.4.1 Guidelines ..................................................................................................... 42

A.4.2 Information Model and Address Space mapping ............................................ 42

A.4.3 Data and error mapping ................................................................................. 46

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SIST EN IEC 62541-8:2020
IEC 62541-8:2020 © IEC 2020 – 3 –

A.4.4 Read data ...................................................................................................... 48

A.4.5 Write data ...................................................................................................... 49

A.4.6 Subscriptions ................................................................................................. 49

Figure 1 – OPC DataItems are linked to automation data ........................................................ 9

Figure 2 – DataItem VariableType hierarchy ......................................................................... 10

Figure 3 – Graphical view of a YArrayItem ............................................................................ 19

Figure 4 – Representation of DataItems in the AddressSpace ............................................... 24

Figure A.1 – Sample OPC UA Information Model for OPC DA ............................................... 34

Figure A.2 – OPC COM DA to OPC UA data and error mapping ............................................ 38

Figure A.3 – Status Code mapping........................................................................................ 39

Figure A.4 – Sample OPC DA mapping of OPC UA Information Model and Address

Space ................................................................................................................................... 43

Figure A.5 – OPC UA to OPC DA data & error mapping ........................................................ 46

Figure A.6 – OPC UA Status Code to OPC DA quality mapping ............................................ 48

Table 1 – DataItemType definition ........................................................................................ 11

Table 2 – BaseAnalogType definition .................................................................................... 12

Table 3 – AnalogItemType definition ..................................................................................... 13

Table 4 – AnalogUnitType definition ...................................................................................... 13

Table 5 – AnalogUnitRangeType definition ........................................................................... 14

Table 6 – DiscreteItemType definition ................................................................................... 14

Table 7 – TwoStateDiscreteType definition ........................................................................... 15

Table 8 – MultiStateDiscreteType definition .......................................................................... 15

Table 9 – MultiStateValueDiscreteType definition ................................................................. 16

Table 10 – ArrayItemType definition ...................................................................................... 17

Table 11 – YArrayItemType definition ................................................................................... 18

Table 12 – YArrayItem item description................................................................................. 20

Table 13 – XYArrayItemType definition ................................................................................. 20

Table 14 – ImageItemType definition .................................................................................... 21

Table 15 – CubeItemType definition ...................................................................................... 22

Table 16 – NDimensionArrayItemType definition ................................................................... 23

Table 17 – Range DataType structure ................................................................................... 25

Table 18 – Range definition .................................................................................................. 25

Table 19 – EUInformation DataType structure ....................................................................... 25

Table 20 – EUInformation definition ...................................................................................... 26

Table 21 – Examples from UNECE Recommendation N° 20 .................................................. 26

Table 22 – ComplexNumberType DataType structure ........................................................... 27

Table 23 – ComplexNumberType definition ........................................................................... 27

Table 24 – DoubleComplexNumberType DataType structure ................................................. 27

Table 25 – DoubleComplexNumberType definition ................................................................ 28

Table 26 – AxisInformation DataType structure ..................................................................... 28

Table 27 – AxisScaleEnumeration values.............................................................................. 28

Table 28 – AxisScaleEnumeration definition ......................................................................... 29

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SIST EN IEC 62541-8:2020
– 4 – IEC 62541-8:2020 © IEC 2020

Table 29 – XVType DataType structure ................................................................................. 29

Table 30 – XVType definition ................................................................................................ 29

Table 31 – Operation level result codes for BAD data quality ................................................ 31

Table 32 – Operation level result codes for UNCERTAIN data quality ................................... 31

Table 33 – Operation level result codes for GOOD data quality ............................................. 31

Table A.1 – OPC COM DA to OPC UA Properties mapping ................................................... 36

Table A.2 – DataTypes and mapping .................................................................................... 39

Table A.3 – Quality mapping ................................................................................................. 40

Table A.4 – OPC DA Read error mapping ............................................................................. 41

Table A.5 – OPC DA Write error code mapping ..................................................................... 41

Table A.6 – DataTypes and Mapping .................................................................................... 47

Table A.7 – Quality mapping ................................................................................................. 48

Table A.8 – OPC UA Read error mapping ............................................................................. 49

Table A.9 – OPC UA Write error code mapping ..................................................................... 49

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SIST EN IEC 62541-8:2020
IEC 62541-8:2020 © IEC 2020 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPC UNIFIED ARCHITECTURE –
Part 8: Data access
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international

co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and

in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,

Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC Publication(s)"). Their

preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with

may participate in this preparatory work. International, governmental and non-governmental organizations liaising

with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for

Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence between

any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.

5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent

rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 62541-8 has been prepared by subcommittee 65E: Devices and

integration in enterprise systems, of IEC technical committee 65: Industrial-process

measurement, control and automation.

This third edition cancels and replaces the second edition published in 2015. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
a) added new VariableTypes for AnalogItems;

b) added an Annex that specifies a recommended mapping of OPC UA Dataccess to OPC

COM DataAccess;
c) changed the ambiguous description of "Bad_NotConnected";

d) updated description for EUInformation to refer to latest revision of UNCEFACT units.

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SIST EN IEC 62541-8:2020
– 6 – IEC 62541-8:2020 © IEC 2020
The text of this International Standard is based on the following documents:
FDIS Report on voting
65E/708/FDIS 65E/726/RVD

Full information on the voting for the approval of this International Standard can be found in the

report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

Throughout this document and the other parts of the IEC 62541 series, certain document

conventions are used:

Italics are used to denote a defined term or definition that appears in the "Terms and definition"

clause in one of the parts of the IEC 62541 series.

Italics are also used to denote the name of a service input or output parameter or the name of

a structure or element of a structure that are usually defined in tables.

The italicized terms and names are, with a few exceptions, written in camel-case (the practice

of writing compound words or phrases in which the elements are joined without spaces, with

each element's initial letter capitalized within the compound). For example, the defined term is

AddressSpace instead of Address Space. This makes it easier to understand that there is a

single definition for AddressSpace, not separate definitions for Address and Space.

A list of all parts of the IEC 62541 series, published under the general title OPC Unified

Architecture, can be found on the IEC website.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates

that it contains colours which are considered to be useful for the correct understanding

of its contents. Users should therefore print this document using a colour printer.

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SIST EN IEC 62541-8:2020
IEC 62541-8:2020 © IEC 2020 – 7 –
OPC UNIFIED ARCHITECTURE –
Part 8: Data access
1 Scope

This part of IEC 62541 is part of the overall OPC Unified Architecture (OPC UA) standard series

and defines the information model associated with Data Access (DA). It particularly includes

additional VariableTypes and complementary descriptions of the NodeClasses and Attributes

needed for Data Access, additional Properties, and other information and behaviour.

The complete address space model, including all NodeClasses and Attributes is specified in

IEC 62541-3. The services to detect and access data are specified in IEC 62541-4.

2 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.
IEC TR 62541-1, OPC Unified Architecture – Part 1: Overview and Concepts
IEC 62541-3, OPC Unified Architecture – Part 3: Address Space Model
IEC 62541-4, OPC Unified Architecture – Part 4: Services
IEC 62541-5, OPC Unified Architecture – Part 5: Information Model
UN/CEFACT: UNECE Recommendation N° 20, Codes for Units of Measure Used in
International Trade, available at
https://www.unece.org/cefact/codesfortrade/codes_index.html
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC TR 62541-1,

IEC 62541-3, and IEC 62541-4 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
DataItem

link to arbitrary, live automation data, that is, data that represents currently valid information

Note 1 to entry: Examples of such data are
• device data (such as temperature sensors),
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SIST EN IEC 62541-8:2020
– 8 – IEC 62541-8:2020 © IEC 2020
• calculated data,
• status information (open/closed, moving),
• dynamically changing system data (such as stock quotes),
• diagnostic data.
3.1.2
AnalogItem

DataItem that represents continuously variable physical quantities (e.g. length, temperature),

in contrast to the digital representation of data in discrete items

Note 1 to entry: Typical examples are the values provided by temperature sensors or pressure sensors. OPC UA

defines a specific VariableType to identify an AnalogItem. Properties describe the possible ranges of AnalogItems.

3.1.3
DiscreteItem

DataItem that represents data that may take on only a certain number of possible values (e.g.

OPENING, OPEN, CLOSING, CLOSED)

Note 1 to entry: Specific VariableTypes are used to identify DiscreteItems with two states or with multiple states.

Properties specify the string values for these states.
3.1.4
ArrayItem

DataItem that represents continuously variable physical quantities and where each individual

data point consists of multiple values represented by an array (e.g., the spectral response of a

digital filter)

Note 1 to entry: Typical examples are the data provided by analyser devices. Specific VariableTypes are used to

identify ArrayItem variants.
3.1.5
EngineeringUnits

units of measurement for AnalogItems that represent continuously variable physical quantities

(e.g. length, mass, time, temperature)

Note 1 to entry: This standard defines Properties to inform about the unit used for the DataItem value and about

the highest and lowest value likely to be obtained in normal operation.
3.2 Abbreviated terms
DA data access
EU engineering unit
UA Unified Architecture
4 Concepts
Data Access deals with the representation and use of automation data in Servers.

Automation data can be located inside the Server or on I/O cards directly connected to the

Server. It can also be located in sub-servers or on other devices such as controllers and

input/output modules, connected by serial links via field buses or other communication links.

OPC UA Data Access Servers provide one or more OPC UA Data Access Clients with
transparent access to their automation data.

The links to automation data instances are called DataItems. The categories of automation data

are
...

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