ISO 25964-1:2011

INTERNATIONAL ISO
STANDARD 25964-1
First edition
2011-08-15


Information and documentation —
Thesauri and interoperability with other
vocabularies —
Part 1:
Thesauri for information retrieval
Information et documentation — Thésaurus et interopérabilité avec
d'autres vocabulaires —
Partie 1: Thésaurus pour la recherche documentaire





Reference number
ISO 25964-1:2011(E)
©
ISO 2011

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ISO 25964-1:2011(E)

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©  ISO 2011
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ISO 25964-1:2011(E)
Contents Page
Foreword .v
Introduction.vi
1 Scope.1
2 Terms and definitions .1
3 Symbols, abbreviated terms and other conventions.12
4 Thesaurus overview and objectives.15
4.1 Overall objective.15
4.2 Vocabulary control and its purpose .16
4.3 Paradigmatic versus syntagmatic relationships.16
4.4 Types of paradigmatic relationship.17
5 Concepts and their scope in a thesaurus.18
5.1 Conceptual basis.18
5.2 Scope notes .20
5.3 Reciprocal scope notes .21
6 Thesaurus terms.21
6.1 Form of terms .21
6.2 Clarification and disambiguation of thesaurus terms .21
6.3 Grammatical form of terms.23
6.4 Capitalization, punctuation and special characters .26
6.5 Singular or plural forms.27
6.6 Selection of the preferred form.30
7 Complex concepts.37
7.1 General .37
7.2 The nature of compound terms .38
7.3 Deciding whether or not to admit a complex concept.39
7.4 How to split a complex concept.43
7.5 Retention of constituent concepts .43
7.6 Consistency in the treatment of complex concepts .44
7.7 Order of words in multi-word terms .44
8 The equivalence relationship, in a monolingual context .44
8.1 General .44
8.2 Synonyms.45
8.3 Quasi-synonyms.48
8.4 Specific terms subsumed in a broader concept .48
8.5 Representation of complex concepts by a combination of terms .49
9 Equivalence across languages .50
9.1 General .50
9.2 Degrees of equivalence .51
9.3 Typical problems and solutions .52
9.4 Representation of cross-language equivalence between preferred terms .57
9.5 Cross-language equivalence between non-preferred terms.57
10 Relationships between concepts.57
10.1 Introduction.57
10.2 The hierarchical relationship .58
10.3 The associative relationship .63
10.4 Customized relationships.67
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ISO 25964-1:2011(E)
11 Facet analysis .68
12 Presentation and layout .70
12.1 General.70
12.2 Alternative display styles.71
12.3 Presentation and layout of multilingual thesauri .80
12.4 Language and character encoding issues.85
13 Managing thesaurus construction and maintenance .88
13.1 Planning a thesaurus .88
13.2 Early stages of compilation.90
13.3 Construction.91
13.4 Introduction to the thesaurus.93
13.5 Dissemination .93
13.6 Updating .95
14 Guidelines for thesaurus management software .98
14.1 General.98
14.2 Size and character limitations.98
14.3 Relationships between terms and between concepts .99
14.4 Notes applying to terms or concepts .100
14.5 Codes and notation .100
14.6 Node labels.100
14.7 Status of languages.100
14.8 Data import/export.101
14.9 Editorial navigation and support.102
14.10 Editorial safeguards .102
14.11 Housekeeping tools.103
15 Data model.103
15.1 General.103
15.2 Notes on the model.105
15.3 Tabular presentation .109
16 Integration of thesauri with applications .115
16.1 Introduction.115
16.2 Interoperability needs for thesauri.116
16.3 Integration with indexing and searching applications.116
17 Exchange formats.118
18 Protocols .119
18.1 General.119
18.2 Purposes and use cases.119
18.3 Application environment and architecture .120
18.4 Thesaurus-specific protocols.120
18.5 General-purpose web database protocols used with thesauri .120
Annex A (informative) Examples of displays found in published thesauri.122
Annex B (informative) XML Schema for data exchange.139
Bibliography .140
Index.144

Table 1 — Symbols and abbreviations. 13
Table 2 — English language tags and their equivalents in other languages . 14
Table A.1 — Tags used in Inspec Thesaurus alphabetical display. 122

Figure 1 — Paradigmatic and syntagmatic relationships. 17

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ISO 25964-1:2011(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 25964-1 was prepared by Technical Committee ISO/TC 46, Information and documentation,
Subcommittee SC 9, Identification and description.
This first edition of ISO 25964-1 cancels and replaces ISO 2788:1986 and ISO 5964:1985, which have been
merged and technically revised. Clauses 1 to 13 of this part of ISO 25964 correspond broadly to the content of
ISO 2788:1986 and ISO 5964:1985. The remaining clauses cover new material.
ISO 25964 consists of the following parts, under the general title Information and documentation — Thesauri
and interoperability with other vocabularies:
⎯ Part 1: Thesauri for information retrieval
The following parts are under preparation:
⎯ Part 2: Interoperability with other vocabularies
This part of ISO 25964 covers the development and maintenance of thesauri, both monolingual and
multilingual, including formats and protocols for data exchange.
ISO 25964-2 will cover interoperability between different thesauri and with other types of structured
vocabulary, such as classification schemes, name authority lists, ontologies, etc., not previously covered in
any International Standard.

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ISO 25964-1:2011(E)
Introduction
Today's thesauri are mostly electronic tools, having moved on from the paper-based era when thesaurus
standards were first developed. They are built and maintained with the support of software and need to
integrate with other software, such as search engines and content management systems. (For example, data
from the thesaurus database might need to be presented in combination with the number of postings found by
a search application.) Whereas in the past thesauri were designed for information professionals trained in
indexing and searching, today there is a demand for vocabularies that untrained users will find to be intuitive,
and for vocabularies that enable inferencing by machines.
ISO 25964 makes the transition that is needed in order to be compatible with the world of electronic
information management. However, this part of ISO 25964 retains the assumption that human intellect is
usually involved in the selection of indexing terms and in the selection of search terms. If both the indexer and
the searcher are guided to choose the same term for the same concept, then relevant documents will be
retrieved. This is the main principle underlying thesaurus design, even though a thesaurus may also be
applied in situations where computers make the choices.
Efficient exchange of data is a vital component of thesaurus management and exploitation. This part of
ISO 25964 therefore includes recommendations for exchange formats and protocols. Adoption of these will
facilitate interoperability between thesaurus management systems and other computer applications, such as
indexing and retrieval systems, that will utilize the data.
This part of ISO 25964 covers development and maintenance of thesauri rather than how to use them in
indexing. Where multilingual issues and examples are addressed, efforts have been made to cover as wide a
selection of languages as possible, consistent with clarity and comprehensibility.
Thesauri are typically used in post-coordinate retrieval systems, but may also be applied to hierarchical
directories, pre-coordinate indexes and classification systems. Increasingly, thesaurus applications need to
mesh with others, such as automatic categorization schemes, free-text search systems, etc. ISO 25964-2 will
address additional types of structured vocabulary (such as classification schemes, name authority lists,
ontologies, etc.) and give recommendations to enable interoperation of the vocabularies at all stages of the
information storage and retrieval process.

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INTERNATIONAL STANDARD ISO 25964-1:2011(E)

Information and documentation — Thesauri and interoperability
with other vocabularies —
Part 1:
Thesauri for information retrieval
1 Scope
This part of ISO 25964 gives recommendations for the development and maintenance of thesauri intended for
information retrieval applications. It is applicable to vocabularies used for retrieving information from all types
of information resources, irrespective of the media used (text, sound, still or moving image, physical object or
multimedia) including knowledge bases and portals, bibliographic databases, text, museum or multimedia
collections, and the items within them.
This part of ISO 25964 also provides a data model and recommended format for the import and export of
thesaurus data.
This part of ISO 25964 is applicable to monolingual and multilingual thesauri.
This part of ISO 25964 is not applicable to the preparation of back-of-the-book indexes, although many of its
recommendations could be useful for that purpose.
This part of ISO 25964 is not applicable to the databases or software used directly in search or indexing
applications, but does anticipate the needs of such applications among its recommendations for thesaurus
management.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
array
group of sibling concepts (2.52)
EXAMPLE
In the following, the sibling concepts outerwear and underwear form an array within the concept “clothing”.
clothing
  outerwear
    overcoats
  underwear

2.2
associative relationship
relationship between a pair of concepts (2.11) that are not related hierarchically but share a strong semantic
connection
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ISO 25964-1:2011(E)
2.3
broader term
preferred term (2.45) representing a concept (2.11) that is broader than the one in question
NOTE The scope of the narrower concept falls completely within the scope of the broader. The relationship between
the two is commonly indicated with the tag BT. For more explanation see 10.2.1.
2.4
characteristic of division
attribute by which a concept (2.11) can be subdivided into an array (2.1) of narrower concepts (2.11), each
having a distinct value of that attribute
cf. facet analysis (2.21), node label (2.38)
EXAMPLE
In the following, age group is the characteristic of division applied to the concept of people:
people
  (people by age group)
  children
  youths
  adults

2.5
classification
classifying
activity involving the components of grouping similar or related things together; separating dissimilar or
unrelated things; and arranging the resulting groups in a logical and helpful sequence
2.6
classification scheme
schedule (2.49) of concepts (2.11) and pre-coordinated combinations of concepts (2.11), arranged by
classification (2.5)
NOTE A classification scheme often also includes an index.
2.7
coined term
new term (2.61) created to express a concept (2.11) for which no suitable term (2.61) exists in the required
language
NOTE For a further explanation and examples, see 6.6.5 and 9.3.3.3
2.8
compound equivalence
relationship or mapping in which one term (2.61) or concept (2.11) in one context is represented by two or
more terms (2.61) or concepts (2.11) in another
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ISO 25964-1:2011(E)
2.9
compound term
term (2.61) that can be split morphologically into separate components
EXAMPLE
In English:
“copper mines” can be split into “copper” and “mines”; “lawnmowers” can be split into “lawns” and “mowers”
In French:
“mine de cuivre” can be split into “mine” and “cuivre”; “biodiversité” can be split into "biologie" and "diversité"
NOTE Compound terms can be multi-word terms, or can consist of only one word.
2.10
computer application
computer program or set of programs that provides high-level processing related to a specific user need
NOTE In ISO 25964, a computer application is sometimes referred to as an application.
2.11
concept
unit of thought
NOTE Concepts can often be expressed in a variety of different ways. They exist in the mind as abstract entities
independent of terms used to express them. They range from the very simple, e.g. “child”, to the very complex, e.g. “child
protection legislation”.
2.12
controlled vocabulary
prescribed list of terms (2.61), headings or codes, each representing a concept (2.11)
NOTE Controlled vocabularies are designed for applications in which it is useful to identify each concept with one
consistent label, for example when classifying documents, indexing them and/or searching them. Thesauri, subject
heading schemes and name authority lists are examples of controlled vocabularies.
2.13
cross-language equivalence
equivalence relationship (2.18) between terms (2.61) representing the same concept (2.11) in different
languages
2.14
data model
abstract model that describes how data is represented and used
NOTE The data model in this part of ISO 25964 provides a generic definition of thesaurus structure and semantics. It
can be used as the basis for defining a database model or an exchange format for thesauri.
2.15
document
any resource that can be classified or indexed in order that the data or information in it can be retrieved
NOTE This definition refers not only to written and printed materials in paper or microform versions (for example,
conventional books, journals, diagrams, maps), but also to non-printed media such as machine-readable and digitized
records, Internet and intranet resources, films, sound recordings, people and organizations as knowledge resources,
buildings, sites, monuments, three-dimensional objects or realia; and to collections of such items or parts of such items.
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ISO 25964-1:2011(E)
2.16
entry term
lead-in term
term (2.61) provided in a controlled vocabulary (2.12), not for direct use in metadata (2.33), but for the
purpose of guiding the user to another term (2.61) that can be used as a category label, subject heading or
preferred term (2.45)
NOTE Entry terms occurring in a thesaurus are generally known as non-preferred terms.
2.17
equivalence mapping
mapping that states that the concept (2.11) in the target vocabulary is considered identical in scope to the
concept (2.11) in the source vocabulary
cf. equivalence relationship (2.18)
2.18
equivalence relationship
relationship between two terms (2.61) in a thesaurus (2.62) that both represent the same concept (2.11)
NOTE In ordinary discourse, terms that are quasi-synonyms may represent slightly different concepts. After inclusion
in the thesaurus, however, the equivalence relationship clarifies that both are regarded as representing the same concept.
When two or more such terms are in the same language within a monolingual or multilingual thesaurus, one of them is
designated a preferred term and the other(s) non-preferred term(s); when two or more such terms are in the different
languages of a multilingual thesaurus, each of them may be a preferred term in its own language respectively, and the
relationship is known as cross-language equivalence.
2.19
exchange format
machine-readable format for representing information that is intended to facilitate exchange of the information
between different applications
NOTE The exchange format for a thesaurus often uses a markup language based on a standard such as XML
[63][64][65][66]
(Extensible Markup Language) , and is based on a data model for thesauri. While the data model provides a
generic description of thesaurus structure and semantics, the exchange format expresses this in a formal language for the
purpose of exchanging thesauri.
2.20
facet
grouping of concepts (2.11) of the same inherent category
EXAMPLE 1 Animals, mice, daffodils and bacteria could all be members of a living organisms facet.
EXAMPLE 2 Digging, writing and cooking could all be members of an actions facet.
EXAMPLE 3 Paris, the United Kingdom and the Alps could all be members of a places facet.
NOTE Examples of high-level categories that can be used for grouping concepts into facets are: objects, materials,
agents, actions, places and times.
cf. node label (2.38)
2.21
facet analysis
analysis of subject areas into constituent concepts (2.11) grouped into facets (2.20), and the subdivision of
concepts (2.11) into narrower concepts (2.11) by specified characteristics of division
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ISO 25964-1:2011(E)
2.22
facet indicator
notational device that indicates the start of a new facet (2.20) within a synthesized compound notation (2.40)
NOTE Examples of facet indicators are the 0 in the Dewey Decimal Classification, and parentheses and quotation
symbols in the Universal Decimal Classification. In the past, the term facet indicator has been used as synonymous with
node label but that usage is deprecated by ISO 25964, to avoid confusion.
2.23
hierarchical relationship
relationship between a pair of concepts (2.11) of which one has a scope falling completely within the scope of
the other
cf. broader term (2.3), narrower term (2.37)
NOTE Several different types of hierarchical relationship exist. For a further explanation, see 10.2.
2.24
homograph
one of two or more words that are written in the same way, but have different meanings
EXAMPLES
In English:
The word "bank" could refer to a financial institution or the
...