ISO/IEC 5394:2024

International
Standard
ISO/IEC 5394
First edition
Information technology — Criteria
2024-01
for concept systems
Technologies de l'information — Critères pour les systèmes de
concept
Reference number
© ISO/IEC 2024
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
© ISO/IEC 2024 – All rights reserved
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviations . 5
4.1 Abbreviations relating to terminology .5
4.2 Abbreviations relating to computing .5
5 Requirements for a concept system . 5
5.1 Overview .5
5.2 Components of a concept system .6
5.2.1 General .6
5.2.2 Concepts .6
5.2.3 Concept relations .7
5.2.4 Terms .7
5.2.5 Definitions .7
5.3 Principles for forming concept systems .7
5.3.1 General .7
5.3.2 Human and computer readability .8
5.3.3 Comprehensiveness .8
5.3.4 Clarity . . .8
5.3.5 Extensibility .8
5.3.6 Stability .8
5.3.7 Retrievability . .8
5.3.8 Standardization .8
5.4 Representations . . .8
5.5 Level of structure .9
5.6 Relations between concept systems and vocabularies .10
5.7 Concept system management .11
5.7.1 Developing concept systems .11
5.7.2 Management of concept systems .11
5.7.3 Integration of concept systems .11
Annex A (informative) Examples of representing various forms of concept systems .12
Annex B (informative) Relationship to ISO/IEC 11179 and other JTC 1/SC 32/WG 2 standards .20
Bibliography .22

© ISO/IEC 2024 – All rights reserved
iii
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
committees established by the respective organization to deal with particular fields of technical activity.
ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations,
governmental and non-governmental, in liaison with ISO and IEC, also take part in the work.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of document should be noted. This document was drafted in accordance with the editorial rules of the ISO/
IEC Directives, Part 2 (see www.iso.org/directives or www.iec.ch/members_experts/refdocs).
ISO and IEC draw attention to the possibility that the implementation of this document may involve the
use of (a) patent(s). ISO and IEC take no position concerning the evidence, validity or applicability of any
claimed patent rights in respect thereof. As of the date of publication of this document, ISO and IEC had not
received notice of (a) patent(s) which may be required to implement this document. However, implementers
are cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents and https://patents.iec.ch. ISO and IEC shall not be held
responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www.iso.org/iso/foreword.html.
In the IEC, see www.iec.ch/understanding-standards.
This document was prepared by Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee
SC 32, Data management and interchange.
Any feedback or questions on this document should be directed to the user’s national standards
body. A complete listing of these bodies can be found at www.iso.org/members.html and
www.iec.ch/national-committees.

© ISO/IEC 2024 – All rights reserved
iv
Introduction
A concept system is a “set of concepts structured in one or more related domains according to the concept
relations among its concepts” according to ISO 1087:2019. A concept is defined as a unit of knowledge
created by a unique combination of characteristics which are the abstraction of a property of an object or of
a set of objects. Concept systems are used to support semantic interoperability and integration in domains,
information classification and organization, indexing, retrieval, etc.
Concept systems are used in the description of semantics of data in the ISO/IEC 11179 series of standards.
ISO/IEC 11179-1 introduces data element concept, object class, property, conceptual domain and value
meaning as concepts. They can be organized through the use of relations among them into concept systems.
A classification scheme is represented as a concept system in ISO/IEC TR 11179-2.
There are various types of concept systems, ranging from the simplest concept systems with simple relations
among concepts to ontologies with rich formal semantics.
The construction of most controlled vocabularies is based on concept systems. On the basis of the relevant
concept system, they add the relationships among terms and establish the relationships among terms and
concepts on the basis of semantic characteristics. Concepts are mainly represented by terms. Therefore, the
discussion of the types of concept systems is inseparable from the discussion of vocabularies.
Ontologies comprise an important kind of concept system. The goals of ontologies are to capture the
knowledge of one or several subject fields and to provide a common understanding. Also, ontologies serve
to determine the common terms in the subject field, and to provide a clear understanding of the relations
among the relevant concepts based on various levels of formal patterns.
The development of artificial intelligence technology and ontology technology has expanded both the content
and the application of the scope of concept systems. The issues regarding the structure, classification,
description and application of concept systems are becoming more and more important.

© ISO/IEC 2024 – All rights reserved
v
International Standard ISO/IEC 5394:2024(en)
Information technology — Criteria for concept systems
1 Scope
This document provides the criteria for effective concept systems. It provides the requirements for
components, formation, representations, structural levels and management of concept systems. Concept
systems are used in the description of semantics of data in ISO/IEC 11179 standards.
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.
ISO 704, Terminology work — Principles and methods
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
object
anything perceivable or conceivable
Note 1 to entry: Objects can be material (e.g. ‘engine’, ‘sheet of paper’, ‘diamond’), immaterial (e.g. ‘conversion ratio’,
‘project plan’) or imagined (e.g. ‘unicorn’, ‘scientific hypothesis’).
[SOURCE: ISO 1087:2019, 3.1.1]
3.2
property
feature of an object (3.1)
EXAMPLE 1 ‘Being made of wood’ as a property of a given ‘table’.
EXAMPLE 2 ‘Belonging to person A’ as a property of a given ‘pet’.
EXAMPLE 3 ‘Having been formulated by Einstein’ as a property of a given ‘E=mc ’.
EXAMPLE 4 ‘Being compassionate’ as a property of a given ‘person’.
EXAMPLE 5 ‘Having a given cable’ as a property of a given ‘computer mouse’.
Note 1 to entry: One or more objects can have the same property.
[SOURCE: ISO 1087:2019, 3.1.3, modified — added the domain .]

© ISO/IEC 2024 – All rights reserved
3.3
characteristic
abstraction of a property (3.2)
EXAMPLE ‘Having a cable for connecting with a computer’ as a characteristic of the concept ‘cord mouse’.
Note 1 to entry: Characteristics are used for describing concepts.
[SOURCE: ISO 1087:2019, 3.2.1]
3.4
concept
unit of knowledge created by a unique combination of characteristics (3.3)
Note 1 to entry: Concepts are not necessarily bound to particular natural languages. They are, however, influenced by
the social or cultural background which often leads to different categorizations.
Note 2 to entry: This is the concept ‘concept’ as used and designated by the term “concept” in terminology work. It is a
very different concept from that designated by other domains such as industrial automation or marketing.
[SOURCE: ISO 1087:2019, 3.2.7]
3.5
domain
subject field
field of special knowledge
Note 1 to entry: The borderlines and the granularity of a domain are determined from a purpose-related point of view.
If a domain is subdivided, the result is again a domain.
[SOURCE: ISO 1087:2019, 3.1.4]
3.6
designation
designator
representation of a concept (3.4) by a sign which denotes it in a domain (3.22) or subject
Note 1 to entry: A designation can be linguistic or non-linguistic. It can consist of various types of characters, but also
punctuation marks such as hyphens and parentheses, governed by domain-, subject-, or language-specific conventions.
Note 2 to entry: A designation can be a term including appellations, a proper name, or a symbol.
[SOURCE: ISO 1087:2019, 3.4.1]
3.7
synonymy
relation between designations (3.6) in a given natural language representing the same concept (3.4)
EXAMPLE Synonymy exists between “deuterium” and “heavy hydrogen”, between “United Nations” and “UN”.
Note 1 to entry: Designations in the relation of synonymy are called “synonyms”.
[SOURCE: ISO 1087:2019, 3.4.23]
3.8
definition
representation of a concept (3.4) by an expression that describes it and differentiates it from related concepts
[SOURCE: ISO 1087:2019, 3.3.1]

© ISO/IEC 2024 – All rights reserved
3.9
term
designation (3.6) that represents a general concept (3.4) by linguistic means
EXAMPLE “laser printer”, “planet”, “pacemaker”, “chemical compound”, “3/4 time”, “Influenza A virus”, “oil
painting”.
Note 1 to entry: Terms may be partly or wholly verbal.
[SOURCE: ISO 1087:2019, 3.4.2]
3.10
vocabulary
terminological dictionary that contains designations (3.6) and definitions (3.8) from one or more domains
(3.22) or subjects
Note 1 to entry: The vocabulary may be monolingual, bilingual or multilingual.
[SOURCE: ISO 1087:2019, 3.7.5]
3.11
controlled vocabulary
CV
vocabulary (3.10) for which the entries, i.e. definition (3.8) /term (3.9) pairs, are controlled by a Source
Authority based on a rulebase and process for addition/deletion of entries
Note 1 to entry: In a controlled vocabulary, there is a one-to-one relationship of definition and term.
EXAMPLE The contents of “Clause 3 Definitions” in ISO/IEC standards are examples of controlled vocabularies
with the entities being identified and referenced through their ID code, i.e., via their clause numbers.
Note 2 to entry: In a multilingual controlled vocabulary, the definition/term pairs in the languages used are deemed to
be equivalent, i.e., with respect to their semantics.
Note 3 to entry: The rule base governing a controlled vocabulary may include a predefined concept system.
Note 4 to entry: Source Authority is defined in ISO/IEC 15944-2:2015, 3.109. Its definition is “Person recognized by
other Persons as the authoritative source for a set of constraints”
[SOURCE: ISO/IEC 15944-5:2008, 3.34, modified — added Note 4 to entry]
3.12
semantic spectrum
range of increasingly precise definitions (3.8)
Note 1 to entry: Generally, the semantic spectrum includes glossaries, classification schemes, taxonomies,
terminologies, subject heading schemes, thesauri, ontologies, etc. according to their semantic precision.
3.13
concept relation
relation between concepts (3.4)
[SOURCE: ISO/IEC 11179-3:2023, 3.2.8]
3.14
hierarchical relation
hierarchical concept relation
generic relation or partitive relation
[SOURCE: ISO 1087:2019, 3.2.12]

© ISO/IEC 2024 – All rights reserved
3.15
associative relation
associative concept relation
pragmatic relation
non-hierarchical concept relation (3.13)
EXAMPLE An associative relation exists between the concepts ‘education’ and ‘teaching’.
[SOURCE: ISO 1087:2019, 3.2.23]
3.16
equivalence relationship
relationship between two designations (3.6) that both represent the same or similar concept (3.4)
3.17
concept system
system of concepts
set of concepts (3.4) structured in one or more related domains (3.22) according to the concept relations
(3.13) among its concepts
[SOURCE: ISO 1087:2019, 3.2.28]
3.18
glossary
terminological dictionary that contains designations (3.6) from one or more domains (3.22) or subjects
together with equivalents in one or more natural languages
Note 1 to entry: In English common language usage, glossary can refer to a monolingual list of designations and
definitions in a domain or subject.
[SOURCE: ISO 1087:2019, 3.7.6]
3.19
classification scheme
descriptive information for an arrangement or division of objects (3.1) into groups based on criteria such as
characteristics (3.3), which the objects have in common
EXAMPLE Origin, composition, structure, application, function, etc.
[SOURCE: ISO/IEC 11179-3:2023, 3.2.5]
3.20
taxonomy
type of hierarchy which deals with generalization/specialization relationships
[SOURCE: ISO/IEC 11179-32:2023, 3.20, modified — Note 1 to entry deleted]
3.21
terminology
set of designations (3.6) and concepts (3.4) belonging to one domain (3.22) or subject
[SOURCE: ISO 1087:2019, 3.1.11]
3.22
subject heading scheme
subject heading language
subject heading list
SHL
structured vocabulary (3.10) comprising terms (3.4) available for subject indexing, plus rules for combining
them into pre-coordinated strings of terms where necessary
[SOURCE: ISO 25964-2:2013, 3.77]

© ISO/IEC 2024 – All rights reserved
3.23
thesaurus
controlled vocabulary (3.11) and structured vocabulary (3.10) in which concepts (3.4) are represented by
terms (3.9), organized so that relationships between concepts are made explicit, and preferred terms are
accompanied by lead-in entries for synonyms or quasi-synonyms
[SOURCE: ISO 5127:2017, 3.8.3.01, modified — Notes to entry deleted.]
3.24
ontology
collection of terms (3.9), relational expressions and associated natural-language definitions (3.8) together
with one or more formal theories designed to capture the intended interpretations of these definitions
[SOURCE: ISO/IEC 21838-1:2021, 3.14, modified — Note 1 to entry deleted]
4 Abbreviations
4.1 Abbreviations relating to terminology
BT Broader Term
NT Narrower Term
RT Related Term
UF Used For
4.2 Abbreviations relating to computing
CSV Comma Separated Values
JSON Java Script Object Notation
OWL Web Ontology Language
RDF Resource Description Framework
UML Unified Modeling Language
XML eXtensible Markup Language
5 Requirements for a concept system
5.1 Overview
A concept system is defined as a set of concepts structured in one or more related domains according to the
concept relations among its concepts according to ISO 1087. Concept systems can be classified as a semantic
spectrum by their increasingly precise definitions. Concept systems can be developed using different
approaches.
The development of information technology and artificial intelligence technology aims to shift as much
complex intelligent work as possible to computer systems. As a consequence, the core issue of artificial
intelligence systems involves the creation of complete knowledge systems coupled with the implementation
of knowledge-based reasoning skills. Using concept systems for abstracting and organizing knowledge has
many benefits. A concept system serves to model concepts and relations among them based on specialized
knowledge of a subject field, helps to form new concepts and terms, forms the basis for a uniform and
standardized terminology, facilitates the implementation of automated reasoning based on certain rules
and facilitate the indexing, retrieval, information organization and navigation of data resources.

© ISO/IEC 2024 – All rights reserved
5.2 Components of a concept system
5.2.1 General
This subclause provides a framework for the use of general concept systems in the information technology
field. This framework describes the basic components and relations making up a general concept system, so
[8][9]
as to assist the construction of different types of concept systems. The UML diagram shown in Figure 1
shows the framework of a general concept system.
A concept system usually consists of (1) a list of concepts, (2) characteristics of concepts, (3) relations among
concepts, and possibly (4) axioms.
Figure 1 — Concept system framework
5.2.2 Concepts
Concepts are the core elements of any concept system. A concept is defined as a unit of knowledge created
by a unique combination of characteristics which are each the abstraction of a property of an object or of
a set of objects according to ISO 1087. An object is defined as anything perceived or conceived. Through
observation and a process of abstraction, objects are categorized into classes, which correspond to units of
knowledge called concepts.
The essential properties of the object are abstracted to form characteristics associated with the mental
representation of the concept. Together, the set formed by these characteristics comprises the intension.
The set of objects conceptualized as a concept is known as the extension of the concept.
Concepts are represented by different kinds of designations, such as terms, abbreviations, appellations, or
even symbols and formulas. In addition, some semantic elements, such as definitions, are used to help to
remove ambiguity, distinguish the concept from others, or to indicate the scope of the concept in concept
systems.
© ISO/IEC 2024 – All rights reserved
5.2.3 Concept relations
Different concepts can have various concept relations according to the differences of their generalized
objects, scope and degree. According to their intension and extension, concepts can not only be divided
into different categories, but also can be assigned to different levels and series, which together constitute
the concept system. ISO 704 and many other works on concepts specify a number of different types of
relations among concepts. There are mainly two types of concept relations used to model a concept system:
(1) hierarchical relation is the relation between two concepts which can be either a generic relation or a
partitive relation, and (2) associative relation is a relation between two concepts derived from underlying
relations between objects.
In a generic relation, the intension of one of the concepts includes that of the other concept and at least one
additional delimiting characteristic. For example, ‘vehicle’ and ‘car’.
In a partitive relation, one of the concepts constitutes the whole and the other concept a part of that whole.
For example, ‘hand’ and ‘finger’, where a finger is a part of hand.
An associative relation illustrates concepts that are interrelated for sequence, space, causality and other
factors. For example, ‘production’ and ‘consumption’ are in sequential relation. For example, ‘action’ and
‘reaction’ are in causal relation. The collection concept relation is also a kind of associative relation in this
document. The collection concept relation that specifies a concept is an element of a collection of concepts.
This relation does not specify the nature of the concept collection nor information about relations among the
concepts that are elements in the concept collection. This relation can be used in glossaries, dictionaries, etc.
The relations among concepts constitutes the structure of a concept system. Some concept systems are
mainly structured by hierarchical relations. Other concept systems can have different kinds of relations,
incorporating generic, partitive, and associative relations within the same overall structural network.
5.2.4 Terms
When naming concepts, it is necessary to form or use appropriate, unambiguous, concise, linguistically
accurate terms (designations) for each concept. The method of naming concepts shall be in accordance with
ISO 704. When a concept is named, it is necessary to establish the relationship between the concept and the
resulting term.
5.2.5 Definitions
Definitions are used to describe concepts. The method of writing definitions shall conform to ISO 704. A
definition does not describe all the characteristics of the concept, but rather should capture the most
essential characteristics required to differentiate the concept from other concepts.
5.3 Principles for forming concept systems
5.3.1 General
The following principles should be followed in the formation of a concept system:
— human and computer readability;
— comprehensiveness;
— clarity;
— extensibility;
— stability;
— retrievability;
— standardization.
© ISO/IEC 2024 – All rights reserved
5.3.2 Human and computer readability
A concept system should not only satisfy human understanding, but also be easy to read by computers. A
concept system should be intuitive for humans to read and understand and available in at least one computer
[8][9]
representation that can be interpreted by computers such as JSON, CSV, XML or UML .
5.3.3 Comprehensiveness
There should be no repetition or obvious omissions of concepts in the subject field that can be relevant to the
targeted audience. A concept system should be complete including all or nearly all relevant concepts needed.
5.3.4 Clarity
A concept system should be understandable to users. The concept relations and criteria of subdivision used
in creating the concept system should be clearly described for users. If the system is too complex it will lose
its explanatory power. Complexity can be avoided by reducing the number of concepts and concept relations.
5.3.5 Extensibility
A concept system should be easy to expand and modify (see ISO 704), such that new concepts can be
introduced to an appropriate position in the concept system. It should also be easy to establish new concept
relations with existing concepts. There should be an organization or individual responsible for extensions of
the concept system if any omissions are found or new requirements are identified.
5.3.6 Stability
A concept system should be stable enough that it will not be easily negated when new theories emerge. It
should be possible to always maintain the relative stability and dynamic balance of the whole system.
5.3.7 Retrievability
The formation and organization of a concept system should be convenient for humans and information
systems to retrieve the concepts they need, such as by using a search engine or information retrieval system.
5.3.8 Standardization
Use standards for principles and methods for terminology development including methods for concept
designations and definitions according to ISO 704. Related standards should be checked to ensure that
existing terms and definitions are used wherever possible.
5.4 Representations
A concept system can be expressed in various styles, such as: text in natural languages, tables, tree graphs,
[8][9] [15] [12][13]
atom graphs, concept diagrams, UML , RDF, Common Logic or OWL 2 , etc.
Concept systems differ with respect to the expressive power of the language used in the specification.
Some conceptualizations require a highly expressive language to define the concepts, whereas others can
be specified using less expressive language depending on the target audience and its needs. An informal
concept system can be expressed only as a list of terms and definitions.
Logical languages have both a formal syntax and a model-theoretic semantics. Examples include RDF,
[12][13] [15]
OWL and Common Logic . Semi-formal languages, such as XML and EXPRESS, have a formal syntax
but sometimes lack model-theoretic semantics. There are also many kinds of concept systems whose terms
and definitions are specified only in natural language. Where a concept system exists in graph-theoretical
form, the concepts occupy the vertices of the graph. The edges of the graph then represent concept relations
between the concepts. A node in a graph can also be called a concept system node.

© ISO/IEC 2024 – All rights reserved
5.5 Level of structure
The level of structure associated with a given concept system corresponds with the strength and richness
of the concept relations among concepts. Concept systems can be classified by the complexity of their
structure, scaled starting with: weakly structured concept systems, hierarchical concept systems, hybrid
concept systems and reason-based concept systems with machine-readable semantics, as shown in Figure 2.
— Weakly structured concept system: a concept system in which concepts are collected as simple sets of
concepts or the concept relation is not obvious, and the terms assigned to concepts are mostly displayed
in a simple way or alphabetical order.
— Hierarchical concept system: a concept system in which all the concepts relate to each other hierarchical,
using generic relation, partitive relation and so on.
— Hybrid concept system: a concept system constructed using a combination of concept relations, including
hierarchical relations and associative relations.
— Reason-based concept system: a concept system in which all the concepts have precise mathematical
descriptions, the concepts and their concept relations are clearly and precisely defined. The concept
system can be used for reasoning, especially for automatic machine reasoning, usually dependent on some
[15] [12][13] [14]
sort of semantic representation (Common Logic , OWL , RDF, UML according to ISO 24156-1 ,
etc.).
© ISO/IEC 2024 – All rights reserved
Key
X richness of concept relation types
Y semantic explicitness
1 weakly structured concept system
2 hierarchical concept system
3 hybrid concept system
4 reason-based concept system
a
Example: Glossary ,Classification scheme.
b
Example: Taxonomy.
c
Example: Terminology, Subject heading scheme, Thesauri.
d
Example: Ontology.
Figure 2 — Level of structure of concept systems
5.6 Relations between concept systems and vocabularies
Concept systems shall be represented by some kind of vocabulary.
Concept systems and vocabularies are interrelated and distinguished from each other. Concept systems are
the basis for constructing vocabularies. Many vocabularies are based on concept systems. However, there
are some differences between concept systems and vocabularies as follows.
— Components. The main component of a concept system is the concept, while the main component of
vocabularies is the designation including terms, appellations, a proper name, or a symbol. A concept is
the basic unit of knowledge, the summary of human cognition at a certain stage, and the crystallization
of human cognition results. Most concepts are represented by terms. Language is the material shell of
thought, while a term is the external language form of a concept. Terms also have phonetic form and
grammatical function, but concepts do not.
— Language neutrality. Terms and concepts are represented in a specific natural language, but a concept
system can be independent of a specific natural language.
— Types of relations. In addition to the concept relations, vocabularies always include the relationships
among terms, such as synonymy, antonymy and equivalence, and the relationships between concepts
and terms, such as mononymy, monosemy, homonymy and polysemy.

© ISO/IEC 2024 – All rights reserved
5.7 Concept system management
5.7.1 Developing concept systems
In the process of concept system construction, there are several issues to be solved.
a) Analyse requirements. Is there a requirements document? Are the requirements clear? Can requirements
be broken down? What are the sources of the requirements? Do two or more requirements conflict with
each other? Is this the latest version of the requirements? What are the old versions of requirements?
Why change requirements? Does the change affect the consistency and integrity of the requirements
document, etc.?
b) Define the domain and scope of the concept system. What is the domain covered by the concept system?
What is the purpose of the concept system? What kind of information does the concept system provide?
Who uses and maintains the concept system, etc.?
c) Consider reusing an existing concept system. Refine and expand existing resources for specific areas
or tasks. If a concept system applies to multiple applications, it can be expedient to reuse the concept
system.
d) Enumerate important concepts and terms in the concept system. Analyse the characteristics of these
concepts, determine which properties comprise essential characteristics, and then build definitions of
concepts. Select the preliminary concepts to be treated by taking into account the subject field, the user
group and their needs.
e) Define concepts and relations among concepts. Determine the transitivity of the relations. Avoid circular
and redundant statements or logic. Analyse coordinate concepts for the concept under consideration.
Determine multiple inheritance relations if they exist.
f) Define the constraints for the properties. Specify the value type, and value domain of any properties.
5.7.2 Management of concept systems
Issues can to be considered in managing concept systems:
— concept system governance;
— policy governing interaction with users;
— policy for making and approving changes to the concept system;
— concept system versioning policy;
— policy for creation and maintenance of identifiers.
5.7.3 Integration of concept systems
Issues can to be considered in integrating concept systems:
— concept system mapping;
— concept system merging;
— concept system alignment.
© ISO/IEC 2024 – All rights reserved
Annex A
(informative)
Examples of representing various forms of concept systems
A.1 Glossaries
A.1.1 General
A glossary is a terminological dictionary which contains a list of designations and their definitions from
a subject field, and can contain equivalents in one or more languages. The traditional aim of glossaries is
to improve the clarity of communication in spoken or written discourse. Traditionally, a glossary appears
at the end of a book and includes terms used in that book that are either newly introduced, uncommon, or
specialized. In the 1990s, it became increasingly common for enterprises to build glossaries for applications
across their entire range of business activities in order to improve the consistency and quality of information
sharing and publishing. Glossary work focuses on creating a complete list of the terminology of domain-
specific terms and acronyms.
A.1.2 Semantic components and relations
The main semantic components of a glossary are designations and definitions.
In a glossary, the “concept” is represented by “designations”. When cases of synonymy arise, one of them
becomes established as a “preferred term”, while acceptable synonyms are simply “admitted terms” and
unacceptable ones become “deprecated terms”.
Some glossaries also associate a definition with each concept. The definition helps to clarify the semantic
boundaries of a concept in order to distinguish this concept from others within the domain.
Glossaries are usually sorted alphabetically for retrieval purposes. Concepts in the glossary usually do not
need to be organized using complex concept relations.
A.1.3 Sample glossary
[23]
The Glossary of Unicode Terms is an example of a glossary, which is updated periodically to stay
synchronized with changes to various standards maintained by the Unicode Consortium. Translations of
[25] [3]
Unicode and ISO/IEC 10646 terminology are also available.
A.2 Classification schemes
A.2.1 General
A classification scheme defines descriptive information for the arrangement or division of objects (ideas)
into groups based on criteria such as the properties associated with the objects (ideas).
The traditional purposes of classification schemes are to organize information resources, whether in hard
copy or electronic, and to allow retrieval by browsing the shelves or by browsing a classified catalogue.
In the metadata field, classification schemes can provide a sound conceptual basis for the development of
metadata having enhanced semantic purity and design integrity. A classification scheme enables users
to find a single object from among a large collection of objects in a metadata registry, and facilitates the
discovery, administration, and analysis of a collection of objects.
Classification schemes have many sub-types. Some types include classification schemes used for records
management, taxonomies and subject classification schemes, etc.

© ISO/IEC 2024 – All rights reserved
[13] [17]
For more on methodologies for developing classification schemes, see ISO 22274 and ISO 25964-2 .
A.2.2 Semantic components and relations
The basic approach of classification is to organize concepts into classes. The main semantic components of
a classification scheme are notations and captions. A notation is a set of symbols representing a concept or a
class in classification schemes. A notation can also take the form of a class code. The caption is the text label
of the class represented by a notation in a classification scheme.
In subject classification schemes, concepts are not usually arranged in hierarchical concept relations. For
example, “chemistry” and “chemical elements” are not represented in any hierarchical concept relations.
However, in a library it is convenient to be able to find books about chemical elements in the chemistry
section. Therefore, the class “chemical elements” can be the sub-class of “chemistry” in subject classification
schemes.
A.2.3 Sample classification scheme
[24]
The Library of Congress Classification (LCC) is an example of a classification scheme. LCC has been
widely used by many libraries. LCC is a classification scheme which was originally designed for organizing
books based on their content. LCC uses Latin letters and Arabic numerals to number the categories. A major
class uses a single letter, such as B for Philosophy/Psychology/Religion, and P for Languages and literature.
In general, two letters are used for subordinate categories, such as PG for Soviet literature and PQ for
Published literature. A real number from 1 to 9999 is added after the letter. For instance, the sub-class for
Spermatophyta under Botany is QK474.8-495.
A.3 Taxonomies
A.3.1 General
The term “taxonomy” is used widely. Taxonomies range from the very simple to the very complex. In the
simplest taxonomies the categories are not necessarily divided into subcategories, while in the complex
ones multiple hierarchical levels can be found. However, in this clause, taxonomy is a collection of controlled
vocabulary terms organized into a hierarchical structure which deals with hierarchical relations such as
genus-species, part-whole, etc. It has some of the same features described in classification schemes, or in
thesauri.
The typical taxonomy is used for classifying or categorizing, organizing, browsing, navigating, searching
and/or filtering any type of content in networked environments. A common use case is to support navigation,
especially by hierarchical organization and browsing through a broad set of electronic resources, e.g.
websites, intranets, portals, wikis. To complement the navigational features with a search capability,
taxonomies can include synonyms operating behind the scenes as entry terms, and “See also” references
between related categories in the hierarchy.
Some taxonomies allow poly-hierarchies, which means that a term can have multiple parents. This means
that if a term appears in multiple places in a taxonomy, then it still remains the same term and applies to the
same concept. Specifically, if a term has children in one place in a taxonomy, then it has the same children in
every other place where it appears.
[17]
For more on methodologies for developing taxonomies, see ISO 25964-2 .
A.3.2 Semantic components and relations
The basic units of a taxonomy are usually known as “categories” or “taxa”. A category can encompass either
a single concept, e.g. “Human rights” or a combination of concepts, e.g. “Government, citizens and rights”. A
combination like this is often created as a presentational device to group several more specif
...