IEC 81346-1:2022

IEC 81346-1
Edition 2.0 2022-03
INTERNATIONAL
STANDARD
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INTERNATIONALE
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HORIZONTAL PUBLICATION
PUBLICATION HORIZONTALE
Industrial systems, installations and equipment and industrial products –
Structuring principles and reference designations –
Part 1: Basic rules
Systèmes industriels, installations et appareils, et produits industriels –
Principes de structuration et désignations de référence –
Partie 1: Règles de base
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IEC 81346-1
Edition 2.0 2022-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
HORIZONTAL PUBLICATION
PUBLICATION HORIZONTALE
Industrial systems, installations and equipment and industrial products –

Structuring principles and reference designations –

Part 1: Basic rules
Systèmes industriels, installations et appareils, et produits industriels –

Principes de structuration et désignations de référence –

Partie 1: Règles de base
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 01.110; 29.020 ISBN 978-2-8322-1077-7

– 2 – IEC 81346-1:2022 © IEC 2022
CONTENTS
FOREWORD . 8
INTRODUCTION . 11
1 Scope . 13
2 Normative references . 13
3 Terms and definitions . 14
4 Concepts . 16
4.1 Object . 16
4.2 Aspect . 17
4.3 Systems . 19
4.4 Structuring . 19
4.5 Function . 19
4.6 Products and components . 20
4.7 Location . 21
4.8 Types. 21
4.9 Object occurrences and product individuals . 21
4.10 Relations between concepts . 22
5 Structuring principles . 23
5.1 General . 23
5.2 Forming structures . 26
5.3 Function-oriented structure . 28
5.4 Product-oriented structure. 29
5.5 Location-oriented structure . 30
5.6 Type-oriented structure . 31
5.7 Structures based on "other aspects" . 31
5.8 Structures based on more than one aspect . 33
6 Construction of reference designations . 34
6.1 General . 34
6.2 Format of reference designations . 35
6.2.1 Single level . 35
6.2.2 Multi-level . 36
6.2.3 Use of letter codes . 36
6.3 Different structures within the same aspect . 37
7 Reference designation set . 37
8 Designation of locations . 39
8.1 General . 39
8.2 Assemblies . 39
9 Presentation of reference designations . 41
9.1 Reference designations . 41
9.2 Reference designation set . 42
9.3 Presentation of identifiers for the top-node . 43
10 Labelling . 44
11 Presentation of properties for an object . 45
12 Application of the reference designation system . 46
Annex A (informative) Information model on the reference designation system . 47
A.1 General . 47

A.2 EXPRESS-G model . 47
A.3 Entity descriptions . 48
A.3.1 object . 48
A.3.2 aspect . 48
A.3.3 object_occurrence . 48
A.3.4 function_occurrence . 48
A.3.5 product_occurrence . 49
A.3.6 location_occurrence. 49
A.3.7 type_occurrence . 49
A.3.8 other_aspect_occurrence. 49
A.3.9 reference_designation . 49
A.3.10 single_level_reference_designation . 49
A.3.11 multi_level_reference_designation . 50
A.3.12 reference_designation_set . 50
A.3.13 classification_scheme . 50
A.3.14 class . 50
A.3.15 top_node_identifier . 51
A.3.16 product_individual . 51
A.4 Enumerations . 51
A.4.1 aspect_kind . 51
A.4.2 81346_classification_domain . 51
A.5 EXPRESS code . 52
Annex B (informative) Establishment and life cycle of objects . 54
B.1 Establishment and validity of objects . 54
B.2 Life cycle story of an object. 55
B.2.1 Overview . 55
B.2.2 Function aspect and function based on a function-oriented structure (A). 55
B.2.3 Functional requirement specification FR1 (B) . 57
B.2.4 Location aspect and reference designation based on a location-oriented
structure (C) . 57
B.2.5 Component type specification CT1 (D) . 57
B.2.6 Function list for system design FL1 and location list for physical design
LL1 (E) . 58
B.2.7 Product specification PS1 (F) . 58
B.2.8 Parts list for manufacturing/installation PL1 (G) . 58
B.2.9 Transport specification (H) . 59
B.2.10 Installation (J) . 59
B.2.11 Commissioning (K) . 59
B.2.12 Acceptance and individual log IL1 (L) . 59
B.2.13 Operation and maintenance (M) . 59
B.2.14 Alternative motor product individual (N) . 60
B.2.15 Alternative motor type and supplier CT2, PS2 (P) . 60
B.2.16 Process modification (R) . 60
B.2.17 Location extension (S) . 60
B.2.18 Etc. (T) . 60
B.2.19 Closing down (U) . 60
B.2.20 Dismantling (V) . 60
B.2.21 Life cycle end (X) . 61
B.3 Discussion on the concept "object" . 61

– 4 – IEC 81346-1:2022 © IEC 2022
B.3.1 Different meanings of "motor" . 61
B.3.2 Definition of "object" . 61
B.4 Discussion on different life cycles . 62
Annex C (informative) Manipulation of objects . 63
C.1 General . 63
C.2 Establishment and validity of objects . 63
C.2.1 Structuring . 63
C.2.2 Ending the structuring . 64
C.2.3 Relations between closely related objects . 64
C.2.4 The roles of the reference designations set . 66
C.2.5 Example . 66
C.3 Life cycle situations . 71
C.3.1 One object for all aspects . 71
C.3.2 One object for each aspect . 72
Annex D (informative) Interpretation of reference designations using different aspects . 74
Annex E (normative) Object represented with several top nodes in an aspect . 77
E.1 General . 77
E.2 Example using aspect shift in structures . 77
E.3 Example using aspect-oriented structures . 78
Annex F (informative) Examples of multiple structures based on the same aspect . 80
F.1 Different function-oriented structures for a process plant . 80
F.2 Topographical location of a system versus locations within an assembly. 81
F.3 Different structuring for different needs . 82
Annex G (normative) Incorporating sub-objects in object structures . 84
G.1 General . 84
G.2 Example. 84
Annex H (informative) Example of reference designations within a system . 88
Annex I (normative) Designation of relations between objects . 94
I.1 General . 94
I.2 Basic principles . 94
I.3 Designation of associative relations . 94
I.4 Classification of relation kinds . 95
I.5 Example of designation of associative relations . 95
Annex J (normative) Requirements for developing sector-specific parts of the
International Standard 81346 series . 97
J.1 General . 97
J.2 81346 framework information model. 97
J.2.1 EXPRESS-G model . 97
J.2.2 Entity descriptions . 98
J.2.3 Enumerations – 81346_classification_domain . 100
J.2.4 EXPRESS code . 102
Annex K (informative) Metadata resource for structure management . 103
Annex L (informative) Recommendations for documentation of the application of the
reference designation system . 105
Annex M (informative) Fundamental ideas for this document. 111
M.1 General . 111
M.2 Basic requirements for a reference designation system . 111
M.3 Required properties for a reference designation system . 111

Annex N (informative) Relationship to other standards . 112
N.1 General . 112
N.2 Use together with ISO/IEC/IEEE 42010:2011 . 112
N.2.1 General . 112
N.2.2 Architecture description and architecture description language . 112
N.3 Use together with IEC 61355-1:2008 . 113
N.3.1 General . 113
N.3.2 Document designation . 113
N.4 Use together with IEC 61175-1:2015 . 114
N.4.1 General . 114
N.4.2 Signal designation . 114
N.5 Use together with IEC 61666:2010 . 115
N.5.1 General . 115
N.5.2 Terminal designation . 115
Bibliography . 116

Figure 1 – International Standards providing a consistent system for designation,

documentation and presentation of information . 12
Figure 2 – Illustration of an object . 17
Figure 3 – Aspects of an object . 18
Figure 4 – Generic relation between the functionality of a technical system and a
technical process . 19
Figure 5 – Example of functionality of a technical system and a technical process . 20
Figure 6 – Illustration of the concept’s product, component, type, individual and
occurrence . 22
Figure 7 – Illustration of structural decomposition of an object from different aspects . 24
Figure 8 – Illustration of a function-oriented decomposition and product-oriented

composition . 25
Figure 9 – Structure tree of object A (alternative 1) . 26
Figure 10 – Structure tree of object A (alternative 2) . 26
Figure 11 – Constituents in one aspect of object type 1 . 27
Figure 12 – Constituents in one aspect of object type 2 . 27
Figure 13 – Constituents in one aspect of object type 5 . 27
Figure 14 – Structure tree of object type 1 . 28
Figure 15 – Illustration of a function-oriented structure . 29
Figure 16 – Illustration of a product-oriented structure . 30
Figure 17 – Illustration of a location-oriented structure . 31
Figure 18 – Example of the use of "other aspect" . 32
Figure 19 – Example of the use of "other aspect" . 33
Figure 20 – Illustration of an object accessible from three aspects, and where these
aspects are used also for internal structuring . 33
Figure 21 – Illustration of an object identified by means of one aspect and with sub-
objects identified by means of another aspect . 34
Figure 22 – Relation between a multi-level reference designation and its single-level
reference designations . 36
Figure 23 – Example of reference designation sets . 38
Figure 24 – Example of designation of mounting planes inside a factory build assembly . 40

– 6 – IEC 81346-1:2022 © IEC 2022
Figure 25 – Examples of designation of locations inside a factory build assembly . 41
Figure 26 – Different objects on a site identified with top node identifiers . 44
Figure 27 – The common initial portion of reference designations . 44
Figure 28 – Labelling of reference designations . 45
Figure 29 – Presentation of a property in combination with a reference designation . 45
Figure A.1 – EXPRESS-G model of the reference designation system . 47
Figure B.1 – Development situations of objects . 54
Figure B.2 – The object’s life cycle . 56
Figure C.1 – Three independently defined objects . 65
Figure C.2 – Three separate objects with mutual relations . 65
Figure C.3 – The three objects are merged into one . 66
Figure C.4 – Overview of the process system . 67
Figure C.5 – Tree-like structures of the system . 67
Figure C.6 – Completed structures of the system . 68
Figure C.7 – Structures with designated sub-objects . 69
Figure C.8 – Structures with some merged-and-shared objects . 69
Figure C.9 – Relations expressed by reference designation sets in which both
designations are unambiguous . 70
Figure C.10 – Relations expressed by reference designation sets in which one

designation is ambiguous . 71
Figure C.11 – Situations in the beginning of an object's life cycle accessible from three
aspects . 71
Figure C.12 – Situations in the beginning of the life cycle of closely related objects,
each accessible from one aspect . 72
Figure D.1 – Shift from function to product aspect . 74
Figure D.2 – Shift from product to function aspect . 74
Figure D.3 – Shift from product to location aspect . 75
Figure D.4 – Shift from location to product aspect . 75
Figure D.5 – Shift from function to location aspect . 76
Figure D.6 – Shift from location to function aspect . 76
Figure E.1 – Object represented with several independent top nodes in one aspect . 77
Figure E.2 – Example of multi-level reference designations using different aspects of
an object with several independent top nodes in one aspect . 78
Figure E.3 – Object represented with several independent top nodes in one aspect
using aspect-oriented structures . 79
Figure F.1 – Illustration of the concept of additional functional views of an industrial
process plant . 80
Figure F.2 – Location-oriented structure of a plant . 81
Figure F.3 – Location-oriented structure within an assembly unit . 81
Figure F.4 – Location-oriented structures of the plant . 82
Figure F.5 – Example of additional product-oriented structures . 83
Figure G.1 – Sub-contractor's design . 85
Figure G.2 – Receiving organization's design . 85
Figure G.3 – Full structure of the receiving organization's design . 86
Figure H.1 – Process flow diagram for a material handling plant . 88

Figure H.2 – Overview diagram of part of the process system (=V1) and part of the
power supply system (=Q1). 89
Figure H.3 – Structure tree for parts of the material handling plant . 90
Figure H.4 – Layout drawing of the components of the MCC =Q1=W1 . 91
Figure H.5 – Layout drawing indicating the location of the MCC . 91
Figure H.6 – Layout drawing of the locations of the MCC =Q1=W1 . 92
Figure H.7 – Motor starter . 92
Figure H.8 – Product- and location-oriented structure trees for the MCC . 93
Figure I.1 – Structure of a relation designation . 95
Figure J.1 – International Standard 81346 framework – An EXPRESS-G model . 98
Figure N.1 – Principle of document designation . 113
Figure N.2 – Signal designation and signal connection identification . 114
Figure N.3 – Principle of terminal designation . 115

Table 1 – Identification of types, occurrences and individuals within different contexts . 23
Table 2 – Examples of single-level reference designations . 35
Table 3 – Examples of multi-level reference designations with multiple prefix signs . 37
Table 4 – Examples of presentations of multi-level reference designations . 42
Table 5 – Presentation of reference designations of a reference designation set . 43
Table C.1 – Possible reference designation sets . 70
Table G.1 – Reference designations in the receiver's design . 87
Table H.1 – Reference designation set for the constituents of the products MCC and
motor starter . 93
Table I.1 – Example of classification scheme for associative relations . 96
Table I.2 – Examples of relation designations . 96
Table K.1 – Metadata elements for reference designation systems . 104
Table L.1 – Documentation on the application of the rules . 105

– 8 – IEC 81346-1:2022 © IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL SYSTEMS, INSTALLATIONS
AND EQUIPMENT AND INDUSTRIAL PRODUCTS –
STRUCTURING PRINCIPLES AND REFERENCE DESIGNATIONS –

Part 1: Basic rules
FOREWORD
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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.
IEC 81346-1 has been prepared by IEC technical committee 3: Documentation, graphical
symbols and representations of technical information, in close cooperation with ISO technical
committee 10: Technical product documentation. It is an International Standard.
It is published as a double logo standard and has the status of a horizontal publication in
accordance with IEC Guide 108.
This second edition cancels and replaces the first edition published in 2009. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the scope includes a reference to IEC Guide 108 for being a horizontal publication;
b) synchronization with IEC 81346-2:2019 and ISO 81346-12:2018;

c) the introduction of the type aspect;
d) introduction of an information model of the reference designation system;
e) introduction of an information model for the framework of reference designation system to
comply with International Standard 81346 series;
f) introduction of recommendation for metadata for design structure management;
g) introduction of rules and method for designation of relations between objects;
h) introduction of requirements for development of sector-specific parts of the International
Standard 81346 series;
i) introduction of requirements for incorporation of sub-object in object structures;
j) introduction of recommendations for documentation of the application of the International
Standard 81346 series;
k) introduced definition of new terms used;
l) new rules added and existing rules modified;
m) notes related to rules are converted to normative text as "Comment to Rule nn".
The text of this International Standard is based on the following documents:
Draft Report on voting
3/1541/FDIS 3/1548/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table. In ISO, the standard has been approved by 10 members out of 11 having cast
a vote.
The language used for the development of this International Standard is English.
A list of parts of the 81346 International Standard, published under the general title Industrial
systems, installations and equipment and industrial products – Structuring principles and
reference designations, can be found on the IEC website.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
In this document, italic type is used as follows:
• terms defined in Clause 3 (applies to the text of Clause 3 only);
• in the description of the EXPRESS model, entity names and attribute identifiers;
• commenting on the story from a structuring and reference designation perspective in
Clause B.2.
– 10 – IEC 81346-1:2022 © IEC 2022
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under 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 publication using a colour printer.

INTRODUCTION
This document establishes a further development of earlier and withdrawn standards on item
designation. It provides the basics for establishing models of plants, machines, buildings,
infrastructure, etc.
This document specifies:
• principles for structuring of objects including associated information;
• rules on forming of reference designations based on the resulting structure.
By applying the structuring principles, even very large sets of information describing a complex
system can be handled efficiently. In Annex B, the life-cycle story of an object shows how
different structures and aspects are related to the sets of information.
The structuring principles and the rules for reference designations:
• are applicable to objects of both physical and non-physical character;
• provide a system
...