ISO 25964-2:2013

INTERNATIONAL ISO
STANDARD 25964-2
First edition
2013-03-15

Information and documentation —
Thesauri and interoperability with other
vocabularies —
Part 2:
Interoperability with other vocabularies
Information et documentation — Thésaurus et interopérabilité avec
d'autres vocabulaires —
Partie 2: Interopérabilité avec d'autres vocabulaires




Reference number
ISO 25964-2:2013(E)
©
ISO 2013

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ISO 25964-2:2013(E)

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©  ISO 2013
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ISO 25964-2:2013(E)
Contents Page
Foreword . v
Introduction . vi
1  Scope . 1
2  Normative references . 1
3  Terms and definitions . 1
4  Symbols, abbreviations and other conventions . 15
5  Objectives and identification . 16
5.1  Objectives of interoperability and mapping . 16
5.2  Identifying the elements to be mapped . 16
6  Structural models for mapping across vocabularies . 16
6.1  General . 16
6.2  Model 1: Structural unity . 17
6.3  Model 2: Direct-linked . 17
6.4  Model 3: Hub structure . 17
6.5  Selective mapping . 19
6.6  Choosing among the options . 20
7  Types of mapping . 20
7.1  General . 20
8  Equivalence mappings. 21
8.1  General . 21
8.2  Simple equivalence . 21
8.3  Compound equivalence . 22
9  Hierarchical mappings . 25
10  Associative mappings. 25
11  Exact, inexact and partial equivalence. 26
11.1  General . 26
11.2  Exact equivalence . 26
11.3  Inexact equivalence . 27
11.4  Partial equivalence . 27
12  Use of mappings in information retrieval . 28
12.1  General . 28
12.2  Human mediation . 28
12.3  Examples of mapping implementation . 29
12.4  Conclusions and recommendations . 30
13  Handling pre-coordination . 31
13.1  General . 31
13.2  Mapping between a thesaurus and a scheme with context-dependent captions . 32
13.3  Mapping more complex classes . 37
14  Techniques for identifying candidate mappings . 38
14.1  General procedure . 38
14.2  Computer assisted direct matching . 40
14.3  Co-occurrence mapping . 40
14.4  Other methods . 40
15  Managing the data . 41
15.1  Types of data to be recorded . 41
15.2  Storing the data . 43
15.3  Maintaining the mappings data . 43
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ISO 25964-2:2013(E)
16  Display of mapped vocabularies .45
16.1  General .45
16.2  Single record display .46
16.3  Complete displays based on one of the vocabularies .48
16.4  Crosswalks .49
17  Classification schemes .50
17.1  Key characteristics and background .50
17.2  Semantic components and relationships compared with thesaurus components .53
17.3  Recommendations for mapping between a thesaurus and a classification scheme .55
18  Classification schemes used for records management .56
18.1  Key characteristics and background .56
18.2  Semantic components and relationships compared with thesaurus components .57
18.3  Recommendations for interoperability with a thesaurus .58
19  Taxonomies .59
19.1  Key characteristics and background .59
19.2  Types of taxonomies .60
19.3  Semantic components and relationships .61
19.4  Mapping between a thesaurus and a taxonomy .63
20  Subject heading schemes .67
20.1  Key characteristics and background .67
20.2  Semantic components and relationships .68
20.3  Mapping subject headings to and from thesaurus concepts .69
21  Ontologies .72
21.1  Key characteristics and background .72
21.2  Semantic components and relationships .73
21.3  Structural comparison between thesauri and ontologies .76
21.4  Interoperability with thesauri .77
22  Terminologies .78
22.1  Key characteristics and background .78
22.2  Semantic components and relationships compared with those of a thesaurus .79
22.3  Interoperability with thesauri .81
23  Name authority lists .81
23.1  Key characteristics and background .81
23.2  Semantic components and relationships .83
23.3  Mapping between a thesaurus and a name authority list .85
24  Synonym rings .87
24.1  Key characteristics and background .87
24.2  Semantic components and relationships .88
24.3  Interoperability with thesauri .89
Annex A (informative) Management of terminological data in support of interoperability .90
Bibliography .93
Index .96

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ISO 25964-2:2013(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 25964-2 was prepared by Technical Committee ISO/TC 46, Information and documentation,
Subcommittee SC 9, Identification and description.
ISO 25964-1:2011, Clauses 1 to 13, correspond broadly to the content of ISO 2788:1986 and ISO 5964:1985.
The remaining clauses of ISO 25964-1, and the whole of this part of ISO 25964, cover new ground not
previously covered in any International Standard.
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
— Part 2: Interoperability with other vocabularies
ISO 25964-1 covers the development and maintenance of thesauri, both monolingual and multilingual,
including formats and protocols for data exchange.
This part of ISO 25964 covers interoperability between different thesauri and with other types of structured
vocabulary.
ISO 25964 covers development and maintenance of thesauri rather than how to use them in indexing, which
is covered by ISO 999.
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ISO 25964-2:2013(E)
Introduction
The ability to identify and locate relevant information among vast collections and other resources is a major
and pressing challenge today, hence the need for semantic interoperability. To support this need, a variety of
web services and other tools are under active development, including (but not limited to):
 registries of vocabularies and metadata schemas,
 repositories of vocabularies and metadata schemas, and
 crosswalk services.
While registries and repositories are outside the scope, this International Standard provides guidance
fundamental to the establishment of crosswalk services. Typically these rely on mapping between different
schemas and vocabularies. Accordingly, inter-vocabulary mapping will be the principal focus of this part of
ISO 25964.
The foundation for discussion of interoperability is laid in ISO 25964-1, which describes the key characteristics
of thesauri and provides guidance on best practice. Unfortunately, however, a comparable International
Standard does not exist for the other types of vocabulary with which a thesaurus needs to interoperate. For
this reason, this second part of ISO 25964 provides some elementary description of other vocabularies such
as classification schemes, subject heading schemes, etc., before making recommendations on mapping
between these and thesauri. It does not provide guidance on the construction of vocabularies other than
thesauri.
Clauses 1 to 12 and Clauses 14 to 16 of this part of ISO 25964 deal with the principles and practicalities of
interoperability, especially mapping, that apply to most vocabularies and especially thesauri. Clause 13
provides additional guidance for handling the pre-coordinated classes that occur in classification schemes and
other vocabularies using the classification approach.
Clauses 17 to 24 are each dedicated to a different type of vocabulary. First priority is given to vocabularies
that are commonly used for classifying or indexing resources, namely classification schemes (including those
used for records management), taxonomies, subject heading schemes and name authority lists.
Notwithstanding their different purposes, terminologies, ontologies and synonym rings are also included. Each
clause provides a brief informative description of the vocabulary’s key characteristics, contrasting its semantic
components with those of a thesaurus, so as to provide context for the interoperability requirements and
recommendations that follow.
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INTERNATIONAL STANDARD ISO 25964-2:2013(E)

Information and documentation — Thesauri and interoperability
with other vocabularies —
Part 2:
Interoperability with other vocabularies
1 Scope
This part of ISO 25964 is applicable to thesauri and other types of vocabulary that are commonly used for
information retrieval. It describes, compares and contrasts the elements and features of these vocabularies
that are implicated when interoperability is needed. It gives recommendations for the establishment and
maintenance of mappings between multiple thesauri, or between thesauri and other types of vocabularies.
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 25964-1:2011, Information and documentation — Thesauri and interoperability with other vocabularies —
Part 1: Thesauri for information retrieval
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
array
group of sibling concepts (3.17)
EXAMPLE
In the following, the sibling concepts outerwear and underwear form an array within the concept clothing.
clothing
  outerwear
    overcoats
  underwear

3.2
associative relationship
relationship between a pair of concepts (3.17) that are not related hierarchically but share a strong semantic
connection
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ISO 25964-2:2013(E)
3.3
broader term
preferred term (3.62) representing a concept (3.17) 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 ISO 25964-1:2011, 10.2.1.
3.4
caption
text label of the class (3.10) represented by a notation (3.54) in a classification scheme (3.12)
NOTE A caption is read in conjunction with its hierarchical context. It does not need to be as complete or as
self-contained as a scope note or even a preferred term in a thesaurus. Captions are sometimes known as class headings
or class names.
3.5
category
concept (3.17) or group of similar or related concepts (3.17) used as a division or subdivision in a taxonomy
(3.83)
NOTE 1 In a classification scheme, such a group is normally called a class.
NOTE 2 This definition of category should not be confused with “fundamental categories”, discussed in
ISO 25964-1:2011 (for example in Clause 12) in the context of faceted classification.
3.6
category label
text label representing a category (3.5) in a taxonomy (3.83)
NOTE The category label in a taxonomy is comparable to the caption in a classification scheme, and although a
category is often referred to as a node, a category label should not be confused with a node label.
3.7
chain index
index to a scheme that represents compound concepts (3.17) by a string of pre-coordinated (3.60) terms
(3.84), such as a classification scheme (3.12), in which entries are generated by successive left truncation
of strings of terms (3.84) representing complex concepts (3.17)
NOTE See the example in 17.2.4, Figure 12.
3.8
characteristic of division
attribute by which a concept (3.17) can be subdivided into an array (3.1) of narrower concepts (3.17) each
having a distinct value of that attribute
cf. node label (3.52)
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
3.9
citation order
order in which preferred terms (3.62) or notations (3.54) are combined in a pre-coordinate (3.60) indexing
(3.36) system or a classification scheme (3.12) to form strings representing complex concepts (3.17)
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ISO 25964-2:2013(E)
3.10
class
concept (3.17) or group of similar or related concepts (3.17) used as a division or subdivision in a
classification scheme (3.12)
NOTE Classes are the basic units of which a classification scheme is constructed. In a taxonomy, although this is a
type of classification scheme, they are generally known as categories (see 3.5). Occasionally they are described as
“nodes”, although they should not be confused with node labels. The term “class” has a different meaning in the context of
ontologies. See 21.2.2.
3.11
classification
classifying
activity involving the components of grouping similar or related things together, separating dissimilar or
unrelated things, and arranging the resulting classes (3.10) in a logical and helpful sequence
3.12
classification scheme
schedule (3.67) of concepts (3.17) and pre-coordinated (3.60) combinations of concepts (3.17), arranged
by classification (3.11)
NOTE A classification scheme often also includes an index.
3.13
collection
set of information resources that can or could be accessed by a structured vocabulary (3.74), whether the
items in the set are collected in one place or distributed over a network
3.14
compound equivalence
relationship between terms (3.84) or mapping (3.41) between concepts (3.17) in which one term (3.84) or
concept (3.17) in one context is represented by two or more terms (3.84) or concepts (3.17) in another
3.15
compound heading
pre-coordinated heading
subject heading (3.76) formed by pre-coordination (3.60) of more than one term (3.84) into a string
EXAMPLE
The single terms Buddhism, Mass media and Religious aspects may be combined to form the compound heading
Mass media — Religious aspects — Buddhism.
3.16
compound term
term (3.84) that can be split morphologically into separate components
EXAMPLES
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.
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ISO 25964-2:2013(E)
3.17
concept
unit of thought
NOTE Concepts can 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”.
3.18
concept group
group of concepts (3.17) selected by some specified criterion, such as relevance to a particular subject area
3.19
controlled vocabulary
prescribed list of terms (3.84), headings or codes, each representing a concept (3.17)
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.
cf. terminology (3.85)
3.20
cross-language equivalence
equivalence relationship (3.28) between terms (3.84) representing the same concept (3.17) in different
languages
3.21
crosswalk
table of mappings (3.41) between the concepts (3.17) in two or more structured vocabularies (3.74)
NOTE Crosswalks support the ability of search engines to search effectively across heterogeneous databases.
3.22
data model
abstract model that describes how data is represented and used
NOTE The data model in ISO 25964-1 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.
3.23
differentiated mapping
mapping (3.40) methodology that aims to distinguish between different types and qualities of mapping (3.41)
NOTE Types of mapping that can be distinguished include equivalence, associative and hierarchical; equivalence
can be further subdivided into simple or compound, and the degree of equivalence can be marked to support further
distinctions at the time of use.
cf. undifferentiated mapping (3.88)
3.24
document
any resource that can be classified (3.11) or indexed in order that the data or information in it may 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 collections of such items or parts of such items.
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ISO 25964-2:2013(E)
3.25
entry term
lead-in term
term (3.84) provided in a controlled vocabulary (3.19), not for direct use in metadata (3.45), but for the
purpose of guiding the user to another term (3.84) which may be used as a category label (3.6), subject
heading (3.76) or preferred term (3.62)
NOTE Entry terms occurring in a thesaurus are generally known as non-preferred terms.
3.26
enumerative classification scheme
classification scheme (3.12) in which all the classes (3.10) available are explicitly listed in the schedules
(3.67)
cf. synthetic classification scheme (3.80)
3.27
equivalence mapping
mapping (3.41) that states that the concept (3.17) in the target vocabulary (3.82) is considered identical in
scope to the concept (3.17) in the source vocabulary (3.72)
cf. equivalence relationship (3.28)
3.28
equivalence relationship
relationship between two terms (3.84) in a thesaurus (3.86) that both represent the same concept (3.17)
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) as 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 i
...