IEC 81346-1:2009

IEC 81346-1
Edition 1.0 2009-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
HORIZONTAL STANDARD
NORME 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 1.0 2009-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
HORIZONTAL STANDARD
NORME 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 978-2-8891-0785-8

– 2 – 81346-1 © IEC:2009
CONTENTS
FOREWORD.6
INTRODUCTION.8
0.1 General.8
0.2 Basic requirements for this standard .8
0.3 Required properties of the standard .9
1 Scope.11
2 Normative references .11
3 Terms and definitions .11
4 Concepts .13
4.1 Object .13
4.2 Aspect.14
4.3 Technical system.15
4.4 Structuring .16
4.5 Function .16
4.6 Products and components .16
4.7 Location .17
4.8 Types, occurrences and individuals .18
5 Structuring principles.20
5.1 General .20
5.2 Forming structures (i.e. types and occurrences) .21
5.3 Function-oriented structure.24
5.4 Product-oriented structure .25
5.5 Location-oriented structure.26
5.6 Structures based on “other aspects” .27
5.7 Structures based on more than one aspect.28
6 Construction of reference designations.29
6.1 General .29
6.2 Format of reference designations .29
6.2.1 Single level.29
6.2.2 Multi-level.30
6.2.3 Use of letter codes .31
6.3 Different structures within the same aspect .31
7 Reference designation set .32
8 Designation of locations .33
8.1 General .33
8.2 Assemblies.33
9 Presentation of reference designations.35
9.1 Reference designations.35
9.2 Reference designations set .36
9.3 Presentation of identifiers for the top-node .37
10 Labelling .38
Annex A (informative) Historical background.39
Annex B (informative) Establishment and life cycle of objects .41
Annex C (informative) Manipulation of objects .52
Annex D (informative) Interpretation of reference designations using different aspects .64

81346-1 © IEC:2009 – 3 –
Annex E (normative) Object represented with several top nodes in an aspect .67
Annex F (informative) Examples of multiple structures based on the same aspect .69
Annex G (informative) Example of structures and reference designations .73
Annex H (informative) Example of reference designations within a system.75
Bibliography.82

Figure 1 – International standards providing a consistent system for designation,
documentation and presentation of information .10
Figure 2 – Illustration of an object.13
Figure 3 – Aspects of an object.15
Figure 4 – Illustration of a function and its sub-functions.16
Figure 5 – Illustration of the concepts product, component, type, individual and
occurrence.19
Figure 6 – Illustration of structural decomposition of an object from different aspects .20
Figure 7 – Illustration of a function-oriented decomposition and product-oriented
composition .21
Figure 8 – Structure tree of object A (alternative 1).22
Figure 9 – Structure tree of object A (alternative 2).22
Figure 10 – Constituents in one aspect of object type 1 .23
Figure 11 – Constituents in one aspect of object type 2 .23
Figure 12 – Constituents in one aspect of object type 5 .23
Figure 13 – Structure tree of object type 1 .24
Figure 14 – Illustration of a function-oriented structure .25
Figure 15 – Illustration of a product-oriented structure .26
Figure 16 – Illustration of a location-oriented structure.27
Figure 17 – Example of the use of “other aspect” .28
Figure 18 – Illustration of an object accessible from three aspects, and where these
aspects are used also for internal structuring.28
Figure 19 – Illustration of an object identified by means of one aspect and with sub-
objects identified by means of another aspect.29
Figure 20 – Examples of single-level reference designations .30
Figure 21 – Relation between a multi-level reference designation and its single-level
reference designations.30
Figure 22 – Examples of multi-level reference designations with multiple prefix signs .31
Figure 23 – Example of reference designation sets.32
Figure 24 – Example of designation of mounting planes inside a factory build assembly .34
Figure 25 – Examples of designation of locations inside a factory build assembly.35
Figure 26 – Examples of presentations of multi-level reference designations .36
Figure 27 – Presentation of reference designations of a reference designation set .37
Figure 28 – Different objects on a site identified with top node identifiers.37
Figure 29 – The common initial portion of reference designations .38
Figure 30 – Labelling of reference designations .38
Figure A.1 – Scope of reference designation standards .39
Figure B.1 – Development situations of an object .41
Figure B.2 – The object’s life cycle .44

– 4 – 81346-1 © IEC:2009
Figure C.1 – Integration of external information by copying.53
Figure C.2 – Integration of an external object by referencing .54
Figure C.3 – Three independently defined objects .54
Figure C.4 – Three separate objects with mutual relations .55
Figure C.5 – The three objects are merged into one.55
Figure C.6 – Overview of the process system .56
Figure C.7 – Tree-like structures of the technical system .57
Figure C.8 – Completed structures of the technical system .58
Figure C.9 – Structures with designated sub-objects.58
Figure C.10 – Structures with some merged-and shared objects .59
Figure C.11 – Relations expressed by reference designation sets in which both
designations are unambiguous.60
Figure C.12 – Relations expressed by reference designation sets in which one
designation is ambiguous.60
Figure C.13 – Situations in the beginning of an object’s life cycle accessible from three
aspects.61
Figure C.14 – Situations in the beginning of the life cycle of closely related objects,
each accessible from one aspect .62
Figure D.1 – Shift from function to product aspect.64
Figure D.2 – Shift from product to function aspect.64
Figure D.3 – Shift from product to location aspect.65
Figure D.4 – Shift from location to product aspect.65
Figure D.5 – Shift from function to location aspect .66
Figure D.6 – Shift from location to function aspect .66
Figure E.1 – Object represented with several independent top nodes in one aspect.67
Figure E.2 – Example of multi-level reference designations using different aspects of
an object with several independent top nodes in one aspect .68
Figure F.1 – Illustration of the concept of additional functional views of an industrial
process plant .69
Figure F.2 – Location-oriented structure of a plant.70
Figure F.3 – Location-oriented structure within an assembly unit .70
Figure F.4 – Location-oriented structures of the plant .71
Figure F.5 – Example of additional product-oriented structures .72
Figure G.1 – Function-oriented structure of object type 1.73
Figure G.2 – Function-oriented structure of object type 2.73
Figure G.3 – Function-oriented structure of object type 5.73
Figure G.4 – Concatenated function-oriented structure tree of object type A .74
Figure H.1 – Process flow diagram for a material handling plant .75
Figure H.2 – Overview diagram of part of the process system (=V1) and part of the
power supply system (=G1) .76
Figure H.3 – Structure tree for parts of the material handling plant .77
Figure H.4 – Layout drawing of the components of the MCC =G1=W1 .78
Figure H.5 – Layout drawing of the locations of the MCC =G1=W1 .79
Figure H.6 – Motor starter.79
Figure H.7 – Product- and location-oriented structure trees for the MCC.80

81346-1 © IEC:2009 – 5 –
Table 1 – Identification of types, occurrences and individuals within different contexts .19
Table C.1 – Possible reference designation sets.59
Table H.1 – Reference designation set for the constituents of the products MCC and
motor starter .81

– 6 – 81346-1  IEC:2009
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL SYSTEMS, INSTALLATIONS
AND EQUIPMENT AND INDUSTRIAL PRODUCTS –
STRUCTURING PRINCIPLES AND REFERENCE DESIGNATIONS –

Part 1: Basic rules
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,
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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
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
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6) All users should ensure that they have the latest edition of this publication.
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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 81346-1 has been prepared by IEC technical committee 3:
Information structures, documentation and graphical symbols, in close co-operation with ISO
technical committee 10: Technical product documentation.
It is published as a double logo standard.
It has the status of a horizontal standard in accordance with IEC Guide 108.
This edition cancels and replaces the first edition of IEC 61346-1, published in 1996. This
edition constitutes a technical revision.
This edition includes the following substantial changes with respect to the first edition of
IEC 61346-1:
– a new introductory clause providing a description and explanation to the concepts used
elsewhere in the publication;
– a more comprehensive description of the structuring principles and rules for structuring
are provided;
81346-1 © IEC:2009 – 7 –
– “other aspects” are introduced, and the prefix sign # is assigned to these aspects;
– the concept of reference designation group has been deleted;
– the specific term “transition” has been avoided and been replaced by an improved textual
description of this phenomenon in annex D;
– a new clause about labelling is introduced;
– the old annexes have been removed with the exception of the annex showing an example
of the application of reference designations within a system;
– a new annex explaining the manipulation of objects is introduced;
– 4 new annexes are introduced as rearrangement of detailed examples or explanatory
information.
The text of this standard is based on the following documents:
FDIS Report on voting
3/947/FDIS 3/958/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table. In ISO, the standard has been approved by 12 members
out of 13 having cast a vote.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the International Standard 81346 series, formerly IEC 61346 series, under
the general title Industrial systems, installations and equipment and industrial products –
structuring principles and reference designations, can be found on the IEC website.
Future standards in this series will carry the new general number 81346. Numbers of existing
standards in this series will be updated at the time of the next edition.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication 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.

– 8 – 81346-1 © IEC:2009
INTRODUCTION
0.1 General
This standard establishes a further development of earlier and withdrawn standards
(IEC 60113-2, IEC 60750) on item designation, see Annex A. It provides basics for
establishing models of plants, machines, buildings etc.
The standard 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 in a complex
installation can be handled efficiently.
The structuring principles and the rules for reference designations are applicable to objects of
both physical and non-physical character.
The structuring principles and the rules for reference designations provide a system that is
easy to navigate within and easy to maintain. This system provides an excellent overview on
a technical system since composite structures are simple to establish and understand.
The structuring principles and the rules for reference designations support alternative design
and engineering processes in the life cycle of an object since they are based on the
successively established results of this process and not on how the engineering process itself
is carried out.
The structuring principles and the rules for reference designations allow, by accepting more
than one aspect, that more than one coding principle can be applied. This technique also
allows ‘old structures’ to be handled together with ‘new structures’ by using multiple
unambiguous identifiers.
The structuring principles and the rules for reference designations support individual
management for the establishment of reference designations, and enable subsequent
integration of modules into larger constructs. They also support the establishment of reusable
modules, either as functional specifications or as physical deliverables.
NOTE The concept of reusable modules encompasses for example, for manufacturers: the establishment of
contract independent modules, and, for operators of complex assemblies: the description of requirements in terms
of supplier independent modules.
The structuring principles and the rules for reference designations support concurrent work
and allow different partners within a project to add and / or remove data to the structured
project result as it proceeds.
The structuring principles and the rules for reference designations recognize time factor within
the life-cycle as important for the application of different structures based on different views
on the considered technical system.
0.2 Basic requirements for this standard
The basic requirements were developed during the preparation of IEC 61346-1 Ed. 1, and
accepted by vote by the national committees.
NOTE These basic requirements concern the development of the structuring principles in this standard and not its
application. They are therefore not normative vis-à-vis the application of this standard.

81346-1 © IEC:2009 – 9 –
• This standard should be applicable to all technical areas and enable a common
application.
• This standard shall be applicable to all kind of objects and their constituents, such as
plants, systems, assemblies, software programs, spaces, etc.
• This standard should be capable of being consistently applied in all phases (i.e.
conceptual development, planning, specification, design, engineering, construction,
erection, commissioning, operation, maintenance, decommissioning, disposal, etc.) of the
life time of an object of interest, i.e. an object to be identified.
• This standard shall provide the ability to identify unambiguously any single object being a
constituent of another object.
• This standard shall support the incorporation of sub-object structures from multiple
organizations into objects from other organizations without change to the original object
structures and neither to the sub-object structures nor any of their documentation.
• This standard shall support a representation of an object independently of the complexity
of the object
• This standard should be easy to apply and the designations should be easy for the user to
understand.
• This standard should support the use of, and should be able to be implemented by,
computer-aided tools for conceptual development, planning, specification, design,
engineering, construction, erection, commissioning, operation, maintenance,
decommissioning, disposal, etc.
0.3 Required properties of the standard
The required properties were developed during the preparation of IEC 61346-1 Ed. 1, and
accepted by vote by the national committees.
NOTE 1 These required properties concern the development of the letter code classification system in this
standard and not its application. They are therefore not normative vis-à-vis the application of this standard.
• This standard shall not contain rules and restrictions that prohibit its use within a technical
area.
• This standard shall cover all its foreseeable applications within all technical areas.
• This standard shall support addressing of information to objects at all phases in their life
time.
• This standard shall allow construction of designations at any time from the currently
available information.
• This standard shall support the identification of objects based on a constituency principle.
• This standard shall contain rules that enable the formulation of unambiguous designations.
• This standard shall be open and allow a designation to be extended.
• This standard shall support modularity and reusability of objects.
• This standard shall support the description of different users’ views on the object
• This standard shall provide rules for the interpretation of designations where needed.
Figure 1 provides an overview on international standards providing a consistent system for
designation, documentation and presentation of information.

– 10 – 81346-1 © IEC:2009
IEC  1386/09
Figure 1 – International standards providing a consistent system for designation,
documentation and presentation of information

NOTE 2 The titles of the publications shown in Figure 1 are not complete.

81346-1 © IEC:2009 – 11 –
INDUSTRIAL SYSTEMS, INSTALLATIONS
AND EQUIPMENT AND INDUSTRIAL PRODUCTS –
STRUCTURING PRINCIPLES AND REFERENCE DESIGNATIONS –

Part 1: Basic rules
1 Scope
This part of IEC 81346, published jointly by IEC and ISO, establishes general principles for
the structuring of systems including structuring of the information about systems.
Based on these principles, rules and guidance are given for the formulation of unambiguous
reference designations for objects in any system.
The reference designation identifies objects for the purpose of creation and retrieval of
information about an object, and where realized about its corresponding component.
A reference designation labelled at a component is the key to find information about that
object among different kinds of documents.
The principles are general and are applicable to all technical areas (for example mechanical
engineering, electrical engineering, construction engineering, process engineering). They can
be used for systems based on different technologies or for systems combining several
technologies.
2 Normative references
The following referenced documents are indispensable for the application 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.
ISO/IEC 646, Information technology – ISO 7-bit coded character set for information
interchange
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
NOTE Terms given in italics are defined elsewhere in this clause.
3.1
object
entity treated in a process of development, implementation, usage and disposal
NOTE 1 The object may refer to a physical or non-physical “thing”, i.e. anything that might exist, exists or did
exist.
NOTE 2 The object has information associated to it.
3.2
system
set of interrelated objects considered in a defined context as a whole and separated from their
environment
– 12 – 81346-1 © IEC:2009
NOTE 1 A system is generally defined with the view of achieving a given objective, e.g. by performing a definite
function.
NOTE 2 Elements of a system may be natural or man-made material objects, as well as modes of thinking and the
results thereof (e.g. forms of organisation, mathematical methods, programming languages).
NOTE 3 The system is considered to be separated from the environment and from the other external systems by
an imaginary surface, which cuts the links between them and the system.
NOTE 4 The term “system” should be qualified when it is not clear from the context to what it refers, e.g. control
system, colorimetric system, system of units, transmission system.
NOTE 5 When a system is part of another system, it may be considered as an object as defined in this standard.
[IEV 151-11-27, modified]
3.3
aspect
specified way of viewing an object
3.4
process
set of interacting operations by which material, energy or information is transformed,
transported or stored
NOTE In the context of this standard the term "process" refers to the industrial process (assembly, construction,
installation, etc.) through which an object is realized.
[IEV 351-21-43, modified]
3.5
function
intended or accomplished purpose or task
3.6
product
intended or accomplished result of labour, or of a natural or artificial process
3.7
component
product used as a constituent in an assembled product, system or plant
3.8
location
intended or accomplished space
3.9
structure
organization of relations among objects of a system describing constituency relations
(consists-of / is-a-part-of)
3.10
identifier
attribute associated with an object to unambiguously distinguish it from other objects within a
specified domain
3.11
reference designation
identifier of a specific object formed with respect to the system of which the object is a
constituent, based on one or more aspects of that system

81346-1 © IEC:2009 – 13 –
3.12
single-level reference designation
reference designation assigned with respect to the object of which the specific object is a
direct constituent in one aspect
NOTE A single-level reference designation does not include any reference designations of upper level or lower
level objects.
3.13
multi-level reference designation
reference designation consisting of concatenated single-level reference designations
3.14
reference designation set
collection of two or more reference designations assigned to an object of which at least one
unambiguously identifies this object
4 Concepts
4.1 Object
The definition of the term ”object” is very general (see 3.1) and covers all items that are
subject to activities in the whole life cycle of a system.
Most objects have a physical existence as they are tangible (e.g. a transformer, a lamp, a
valve, a building). However, there are objects that do not have a physical existence but exist
for different purposes, for example:
• an object exists only by means of the existence of its sub-objects, thus the considered
object is defined for structuring purposes (i.e. a system);
• for identification of a set of information.
This international standard does not distinguish between those objects that have a physical
existence and those that have not. Both kinds of objects can be relevant for being identified
and handled in the life-cycle of a system.
There are no genuine rules on how an object is established. In fact, it is the designer/engineer
who decides that an object exists and establishes the need to identify this object.
When an object is established, information may be associated with it. This information may
change throughout the life cycle of that object
Figure 2 illustrates an object where the surface of each side of the cube represents one
aspect of the object. This representation of an object is used in further figures for the
explanation of the concepts.
IEC  1387/09
Figure 2 – Illustration of an object

– 14 – 81346-1 © IEC:2009
An object is established when there is a need for that particular object.
An object is removed when the object is no longer needed.
NOTE 1 The object may also be removed when its properties are found to be covered by another object. This is
frequently the case during engineering when objects initially may have been distinctively subdivided and later are
found possible to be combined or merged.
NOTE 2 The removal/deletion of a physical object is not the same as the complete deletion of the object, as the
information on the object may be kept for retention reasons.
4.2 Aspect
If interior objects of an object or the interrelations of this object to other objects are to be
studied, it is useful to look at these objects from different views. For the purpose of this
international standard, these views are called aspects.
Aspects act like filters on an object, see Figure 3, and "highlight" the information that is of
relevance. The aspects dealt with in this international standard are focused on:
• what an object is intended to do or what it actually does – the function aspect;
• by which means an object does what it is intended to do – the product aspect;
• intended or actual space of the object – the location aspect.
In addition other aspects may be applied when none of the three above are applicable or
sufficient (see 5. 6) .
The aspect concept is, in this international standard, used for structuring purposes.
Looking at an object under an aspect, only constituent objects (i.e. sub-objects) are seen that
are relevant in that aspect. Other sub-objects may exist but they have then no relevance in
the considered aspect. On the other hand, it may happen that a sub-object is seen under
different aspects, if this sub-object has relevance in all those aspects.
When a sub-object is recognized by means of an aspect of an object, all available information
on the sub-object is accessible, including information related to its other aspects.

81346-1 © IEC:2009 – 15 –
IEC  1388/09
Figure 3 – Aspects of an object
4.3 Technical system
A “technical system” is a group of components working together for a specific purpose.
The technical system is the “infrastructure” for a process consisting of a number of activities,
such as cooking, screening, transporting, welding, and driving, to achieve the intended
outcome. The components of the technical system are the static prerequisite for the dynamic
activities of the process.
NOTE One and the same component may be part of (play a role in) more than one technical system.
A technical system can be delivered as a completed assembled system. The components of
the technical system can, however, be delivered individually or as assembled parts; possibly
of other systems. The technical system is in that case completed during the installation and
connection of the components.
In the context of structuring, the technical system is seen as an object and its components as
physical sub-objects.
– 16 – 81346-1 © IEC:2009
4.4 Structuring
In order for a system to be efficiently specified, designed, manufactured, serviced or
operated,
...