ISO 21127
(Main)Information and documentation — A reference ontology for the interchange of cultural heritage information
Information and documentation — A reference ontology for the interchange of cultural heritage information
ISO 21127:2014 establishes guidelines for the exchange of information between cultural heritage institutions. In simple terms, this can be defined as the information managed by museums, libraries, and archives. The intended scope of this ISO 21127:2014 is defined as the exchange and integration of heterogeneous scientific documentation relating to museum collections. This definition requires further elaboration.
Information et documentation — Une ontologie de référence pour l'échange d'informations du patrimoine culturel
L'ISO 21127:2014 fixe des lignes directrices pour l'échange d'informations entre institutions patrimoniales. En termes simples, on peut dire qu'il s'agit de l'information gérée par les musées, les bibliothèques et les archives. Le domaine d'application visé par l'ISO 21127:2014 porte sur l'échange et l'intégration de la documentation scientifique hétérogène relative aux collections muséales. Cette définition appelle un développement.
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ISO/DIS PRF 21127:2022(E) .
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ISO/TC 46/SC 4
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Secretariat: KATS
Third edition
2022-10-25
Date: 2023-08-16
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Information and documentation — A reference ontology for the
interchange of cultural heritage information
Information et documentation — Une ontologie de référence pour l'échange d'informations du patrimoine Formatted
...
culturel
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ISO/DISPRF 21127:20222023(E)
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© ISO 20222023
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All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this
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including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can
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ISO Copyright Officecopyright office
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ISO/DISPRF 21127:20222023(E)
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Contents
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Foreword v Formatted: Font: Bold
Introduction vii
1 Scope 1
2 Normative references 1
3 Terms and definitions 1
4 Objectives 9
5 Compatibility 10
6 Applied form 11
7 Modelling principles 16
8 Introduction to the basic concepts 24
9 Class declarations 42
10 Property declarations 98
Annex A (informative) Scope Precision 188
Annex B (informative) Deprecated classes and properties 189
Bibliography 193
Foreword . v
Introduction . vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Objectives . 9
5 Compatibility . 10
6 Applied form . 11
6.1 General. 11
6.2 Naming conventions. 11
6.3 Inheritance and transitivity . 12
6.4 Shortcuts . 13
6.5 Logical expressions used in ISO 21127 . 13
6.6 Property quantifiers . 15
7 Modelling principles . 16
7.1 Reality, knowledge bases and ISO 21127 . 16
7.2 Authorship of knowledge base (KB) contents . 18
7.3 Extensions . 19
7.4 Minimality . 21
7.5 Monotonicity . 21
7.5.1 Open World principle . 21
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ISO/DISPRF 21127:20222023(E)
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7.5.2 Monotonicity of the document . 22
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7.5.3 Monotonicity of the data . 22
7.5.4 Monotonicity of the knowledge base . 23
7.5.5 Monotonicity and time-dependent properties . 23
7.6 Disjointness . 23
8 Introduction to the basic concepts . 24
8.1 General. 24
8.2 Relations with events . 26
8.2.1 General . 26
8.2.2 Spatial relations . 31
8.2.3 Temporal relations . 33
8.2.4 Spatiotemporal relations . 35
8.3 Specific modelling constructs . 37
8.3.1 Types . 37
8.3.2 Temporal relation primitives based on fuzzy boundaries . 39
9 Class declarations . 42
10 Property declarations. 98
Annex A (informative) Scope precision — Intended scope . 188
Annex B (informative) Deprecated classes and properties . 189
Bibliography . 193
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ISO/DISPRF 21127:20222023(E)
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Foreword
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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.
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 ISO documentsdocument should be noted. This document was drafted in accordance
with the editorial rules of the ISO/IEC Directives, Part 2 (see
www.iso.org/directiveswww.iso.org/directives).
Attention is drawnISO draws attention to the possibility that some of the elementsimplementation of this
document may beinvolve the subjectuse of (a) patent(s). ISO takes 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 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. ISO shall not be held
responsible for identifying any or all such patent rights. Details of any patent rights identified during the
development of the document will be in the Introduction and/or on the ISO list of patent declarations
received (see www.iso.org/patents).
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.htmlwww.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 46, Information and documentation,
Subcommittee SC 4, Technical interoperability., in collaboration with the International Committee for
Documentation (CIDOC).
This third edition cancels and replaces the second edition (ISO 21127:2014), which has been technically
revised.
The main changes are as follows:
— — deprecated 13 overspecialised classes and 15 overspecialized properties;
— — added 8 properties to replace 8 deprecated properties in order to support chronological
reasoning;
— — added 4 (sub)classes and 17 properties to align with OCG standards for geospatial data;
— — added 4 (sub)classes and 12 properties for more detailed conceptualizations of existing concepts;
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ISO/DISPRF 21127:20222023(E)
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— — provided further clarification of concepts through the addition real-life examples, references, and
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first order logic axioms;
— — extended explanatory introductory sections to clarify the standard and its maintained scope.
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.htmlwww.iso.org/members.html.
The committee responsible for this document is ISO/TC 46, Information and documentation,
Subcommittee SC 4, Technical interoperability, in collaboration with the International Council of
Museums Committee for Documentation (ICOM CIDOC).
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ISO/DISPRF 21127:20222023(E)
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Introduction
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This document is the culmination of more than a decade of standards development work by the
International Committee for Documentation (CIDOC) of the International Council of Museums (ICOM).
Work on this document began in 1996 under the auspices of the ICOM-CIDOC Documentation Standards
1
Working Group. The document provided by CIDOC formed the basis for ISO 21127 which was first
published in 2006. While the initial impetus for the work came from the museum community, it has since
spread to encompass other types of cultural heritage institution. This document has been appropriated
and extended to meet the needs of other institutions dealing with cultural heritage.
The primary purpose of this document is to offer a conceptual basis for the integration, mediation, and
exchange of information between cultural heritage organizations such as museums, libraries, and
archives. This document aims to provide a common reference point against which divergent and
incompatible sources of information can be compared and, ultimately, harmonized.
2
ISO 21127 is an ontology for cultural heritage information: a formal representation of the conceptual
scheme, or “world view”, underlying the database applications and documentation systems that are used
by cultural heritage institutions. It is important to note that this document aims to clarify the logic of what
cultural heritage institutions do in fact document; it is not intended as a normative specification of what
they should document. The primary role of this document is to enable information exchange and
integration between heterogeneous sources of cultural heritage information. It aims to provide the
semantic definitions and clarifications needed to transform disparate, localized information sources into
a coherent global resource, be it within an institution, an intranet, or on the Internet.
The specific aims of this document are to
— — serve as a common language for domain experts and IT developers when formulating
requirements,
— — serve as a formal language for the identification of common information contents in different data
formats; in particular to support the implementation of automatic data transformation algorithms
from local to global data structures without loss of meaning. These transformation algorithms are
useful for data exchange, data migration from legacy systems, data information integration, and
mediation of heterogeneous sources,
— — support associative queries against integrated resources by providing a global model of the basic
classes and their associations to formulate such queries, and
— — provide developers of information systems with a guide to good practice in conceptual modelling.
The ISO 21127 ontology is expressed as a series of interrelated concepts with definitions. This
presentation is similar to that used for a thesaurus. However, the ontology is not intended as a
terminology standard and does not set out to define the terms that are typically used as data in cultural
heritage documentation. Although the presentation provided here is complete, it is an intentionally
compact and concise presentation of the ontology's 81 classes and 160 unique properties. It does not
attempt to articulate the inheritance of properties by subclasses throughout the class hierarchy.
1
The CIDOC CRM Special Interest Group continues to maintain a version of this original document, usually Formatted: Adjust space between Latin and Asian text, Adjust
[15] [15]
space between Asian text and numbers
known as the “CIDOC Conceptual Reference Model” or CIDOC CRM . .
2
In the sense used in computer science, i.e.,. it describes in a formal language the relevant explicit and
implicit concepts and the relationships between them.
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ISO/DISPRF 21127:20222023(E)
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However, this definition does contain all the information needed to infer and automatically generate a
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3
full declaration of all properties, including inherited properties.
3
A class and property reference hierarchy can be found in Reference [15].[15].
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DRAFT INTERNATIONAL STANDARD ISO/DIS 21127:2022(E)
Information and documentation — A reference ontology for the
interchange of cultural heritage information
1 Scope
This document gives a curated, factual knowledge about the past at a human scale. It specifies all
information required for the exchange and integration of heterogeneous scientific and scholarly
documentation about the past at a human scale and the available documented and empirical evidence for
4
this.
A more detailed and useful definition can be articulated by defining both the intended scope, a broad and
maximally-inclusive definition of general application principles, and the practical scope, which is
expressed by the overall scope of a growing reference set of specific, identifiable documentation
standards and practices that this document aims to semantically describe, restricted, always, in its details
to the limitations of the intended scope.
5
The practical scope of this document is expressed in terms of the set of reference standards and de facto
standards for documenting factual knowledge. This document covers the same domain of discourse as
the union of these reference standards; this means that for data correctly encoded according to these
documentation formats there can be an ISO 21127-compatible expression that conveys the same
meaning.
2 Normative references
There are no normative references in this document.
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3 Terms and definitions
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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: Formatted: English (United Kingdom)
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— — ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp
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— — IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/
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3.1
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class
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category of items that share one or more common traits serving as criteria to identify the items belonging
to the class
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space between Asian text and numbers
Note 1 to entry: These properties need not be explicitly formulated in logical terms, but may be described in a text
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(here called a scope note) that refers to a common conceptualisation of domain experts. The sum of these traits is
space between Asian text and numbers, Tab stops: Not at 0.7
cm + 1.4 cm + 2.1 cm + 2.8 cm + 3.5 cm + 4.2 cm + 4.9
called the intension of the class. A class may be the domain or range of none, one or more properties formally defined
cm + 5.6 cm + 6.3 cm + 7 cm
in a model. The formally defined properties need not be part of the intension of their domains or ranges: such
properties are optional. An item that belongs to a class is called an instance of this class. A class is associated with
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4
Annex A Annex A elaborates on this definition.
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5
The practical scope of ISO 21127, including a list of the relevant museum documentation standards, is
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discussed in more detail on the CIDOC CRM website at < https://cidoc-crm.org/scope.html >.https://cidoc-
crm.org/scope.html >.
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an open set of real-life instances, known as the extension of the class. Here “open” is used in the sense that it is
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generally beyond our capabilities to know all instances of a class in the world and indeed that the future may bring
new instances about at any time (Open World). Therefore, a class cannot be defined by enumerating its instances.
A class plays a role analogous to a grammatical noun, and can be completely defined without reference to any other
construct (unlike properties, which shall have an unambiguously defined domain and range). In some contexts, the
terms individual class, entity or node are used synonymously with class. For example, “Person” is a class. To be a
“Person” may actually be determined by DNA characteristics, but everyone knows what a “Person” is. A “Person”
may have the property of being a member of a “Group”, but it is not necessary to be member of a “Group” in order
to be a “Person”. It is impossible to know all the "Persons" of the past. There will be more “Person” in the future.
3.2
complement
set of all instances of B that are not instances of A
Note 1 to entry: Formally, it is the set-theoretic difference of the extension of B minus the extension of A.
Compatible extensions of the CIDOC CRM should not declare any class with the intension of them being the
complement of one or more other classes. To do so will normally violate the desire to describe an Open World. For
example, for all possible cases of human gender, male should not be declared as the complement of female or vice
versa. What if someone is both or even of another kind?
3.3
disjoint
having no common instances (3.8)(3.8) in any possible world
Note 1 to entry: Classes are disjoint if the intersection of their extensions is an empty set.
3.4
domain
class (3.1)(3.1) for which a property is formally defined
Note 1 to entry: This means that instances of the property are applicable to instances of its domain class. A
property shall have exactly one domain, although the domain class may always contain instances for which the
property is not instantiated. The domain class is analogous to the grammatical subject of the phrase for which the
property is analogous to the verb. It is arbitrary which class is selected as the domain and which as the range, just
as the choice between active and passive voice in grammar is arbitrary. Property names in this document are
designed to be semantically meaningful and grammatically correct when read from domain to range. In addition,
the inverse property name, normally given in parentheses, is also designed to be semantically meaningful and
grammatically correct when read from range to domain.
3.5
endurant
entities which are wholly present at any time they are present (Reference [87], pp. 166-181)
Note 1 to entry: See Reference [87], pp. 166-181.
3.6
extension
set of all real-life instances belonging to the class that fulfil the criteria of its intension (3.9)(3.9)
Note 1 to entry: The extension of a class is “open” in the sense that it is generally beyond our capabilities to know
all instances of a class in the world and indeed that the future may bring new instances about at any time (Open
World). An information system may at any point in time refer to some instances of a class, which form a subset of
its extension.
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3.7
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inheritance
duplication of properties from a class to its subclasses
Note 1 to entry: Inheritance of properties from superclasses to subclasses means that if an item x is an instance
of a class A, then all properties that shall hold for the instances of any of the superclasses of A shall also hold for
item x, and that all optional properties that may hold for the instances of any of the superclasses of A may also hold
for item x.
3.8
instance
items having properties that meet the criteria of the intension (3.9)(3.9) of the classes
Note 1 to entry: The number of instances declared for a class in an information system is typically less than the
total in the real world. For example, the reader is an instance of Person, but they are not mentioned in all information
systems describing Persons.
Note 2 to entry: For example, the painting known as the “The Mona Lisa” is an instance of the class E22 Human-
Made Object. An instance of a property is a factual relation between an instance of the domain and an instance of
the range of the property that matches the criteria of the intension of the property. For example, “The Mona Lisa”
has former or current owner. The Louvre is an instance of the property P51 has former or current owner (is former
or current owner of).
3.9
intension
intended meaning of a class
Note 1 to entry: The intension of a class consists of one or more common traits shared by all instances of the class
or property. These traits need not be explicitly formulated in logical terms, but may just be described in a text (here
called a scope note) that refers to a conceptualisation common to domain experts.
3.10
interoperability
capability of different information systems to communicate some of their contents
Note 1 to entry: Interoperability may mean that two systems can exchange information, and/or that multiple
systems can be accessed with a single method.
Note 2 to entry: Generally, syntactic interoperability is distinguished from semantic interoperability. Syntactic
interoperability means that the information encoding of the involved systems and the access protocols are
compatible, so that information can be processed as described above without error. However, this does not mean
that each system processes the data in a manner consistent with the intended meaning. For example, one system
may use a table called “Actor” and another one called “Agent”. With syntactic interoperability, data from both tables
may only be retrieved as distinct, even though they may have exactly the same meaning. To overcome this situation,
semantic interoperability has to be added. This document relies on existing syntactic interoperability and is
concerned only with adding semantic interoperability (3.24).(3.24).
3.11
inverse of
reinterpretation of a property from range to domain without more general or more specific meaning
Note 1 to entry: The inverse of a property is similar to the choice between active and passive voice in some
languages. In contrast to some knowledge representation languages, such as RDF and OWL, this document regards
that the inverse of a property is not a property in its own right that needs an explicit declaration of being inverse of
another, but an interpretation implicitly existing for any property. The inverse of the inverse of a property is
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ISO
...
INTERNATIONAL ISO
STANDARD 21127
Third edition
Information and documentation — A
reference ontology for the interchange
of cultural heritage information
Information et documentation — Une ontologie de référence pour
l'échange d'informations du patrimoine culturel
PROOF/ÉPREUVE
Reference number
ISO 21127:2023(E)
© ISO 2023
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ISO 21127:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
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
ii
PROOF/ÉPREUVE © ISO 2023 – All rights reserved
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ISO 21127:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Objectives . 9
5 Compatibility .10
6 Applied form .10
6.1 General . 10
6.2 Naming conventions . 11
6.3 Inheritance and transitivity . 12
6.4 Shortcuts . 12
6.5 Logical expressions used in ISO 21127 .12
6.6 Property quantifiers. 14
7 Modelling principles .15
7.1 Reality, knowledge bases and ISO 21127 . 15
7.2 Authorship of knowledge base (KB) contents . 17
7.3 Extensions . 17
7.4 Minimality . 19
7.5 Monotonicity . 20
7.5.1 Open World principle .20
7.5.2 Monotonicity of the document . 20
7.5.3 Monotonicity of the data . 21
7.5.4 Monotonicity of the knowledge base . . 21
7.5.5 Monotonicity and time-dependent properties . 21
7.6 Disjointness .22
8 Introduction to the basic concepts .22
8.1 General .22
8.2 Relations with events . 24
8.2.1 General . 24
8.2.2 Spatial relations . 27
8.2.3 Temporal relations.29
8.2.4 Spatiotemporal relations . 31
8.3 Specific modelling constructs .33
8.3.1 Types . 33
8.3.2 Temporal relation primitives based on fuzzy boundaries .34
9 Class declarations .37
10 Property declarations .91
Annex A (informative) Scope precision — Intended scope .175
Annex B (informative) Deprecated classes and properties .176
Bibliography .179
iii
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ISO 21127:2023(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.
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 ISO 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).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes 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 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. ISO 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.
This document was prepared by Technical Committee ISO/TC 46, Information and documentation,
Subcommittee SC 4, Technical interoperability, in collaboration with the International Committee for
Documentation (CIDOC).
This third edition cancels and replaces the second edition (ISO 21127:2014), which has been technically
revised.
The main changes are as follows:
— deprecated 13 overspecialised classes and 15 overspecialized properties;
— added 8 properties to replace 8 deprecated properties in order to support chronological reasoning;
— added 4 (sub)classes and 17 properties to align with OCG standards for geospatial data;
— added 4 (sub)classes and 12 properties for more detailed conceptualizations of existing concepts;
— provided further clarification of concepts through the addition real-life examples, references, and
first order logic axioms;
— extended explanatory introductory sections to clarify the standard and its maintained scope.
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.
iv
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---------------------- Page: 4 ----------------------
ISO 21127:2023(E)
Introduction
This document is the culmination of more than a decade of standards development work by the
International Committee for Documentation (CIDOC) of the International Council of Museums (ICOM).
Work on this document began in 1996 under the auspices of the ICOM-CIDOC Documentation Standards
1)
Working Group. The document provided by CIDOC formed the basis for ISO 21127 which was first
published in 2006. While the initial impetus for the work came from the museum community, it
has since spread to encompass other types of cultural heritage institution. This document has been
appropriated and extended to meet the needs of other institutions dealing with cultural heritage.
The primary purpose of this document is to offer a conceptual basis for the integration, mediation,
and exchange of information between cultural heritage organizations such as museums, libraries,
and archives. This document aims to provide a common reference point against which divergent and
incompatible sources of information can be compared and, ultimately, harmonized.
2)
ISO 21127 is an ontology for cultural heritage information: a formal representation of the conceptual
scheme, or “world view”, underlying the database applications and documentation systems that are
used by cultural heritage institutions. It is important to note that this document aims to clarify the logic
of what cultural heritage institutions do in fact document; it is not intended as a normative specification
of what they should document. The primary role of this document is to enable information exchange
and integration between heterogeneous sources of cultural heritage information. It aims to provide the
semantic definitions and clarifications needed to transform disparate, localized information sources
into a coherent global resource, be it within an institution, an intranet, or on the Internet.
The specific aims of this document are to
— serve as a common language for domain experts and IT developers when formulating requirements,
— serve as a formal language for the identification of common information contents in different data
formats; in particular to support the implementation of automatic data transformation algorithms
from local to global data structures without loss of meaning. These transformation algorithms are
useful for data exchange, data migration from legacy systems, data information integration, and
mediation of heterogeneous sources,
— support associative queries against integrated resources by providing a global model of the basic
classes and their associations to formulate such queries, and
— provide developers of information systems with a guide to good practice in conceptual modelling.
The ISO 21127 ontology is expressed as a series of interrelated concepts with definitions. This
presentation is similar to that used for a thesaurus. However, the ontology is not intended as a
terminology standard and does not set out to define the terms that are typically used as data in cultural
heritage documentation. Although the presentation provided here is complete, it is an intentionally
compact and concise presentation of the ontology's 81 classes and 160 unique properties. It does
not attempt to articulate the inheritance of properties by subclasses throughout the class hierarchy.
However, this definition does contain all the information needed to infer and automatically generate a
3)
full declaration of all properties, including inherited properties.
1) The CIDOC CRM Special Interest Group continues to maintain a version of this original document, usually known
[15]
as the “CIDOC Conceptual Reference Model” or CIDOC CRM .
2) In the sense used in computer science, i.e. it describes in a formal language the relevant explicit and implicit
concepts and the relationships between them.
3) A class and property reference hierarchy can be found in Reference [15].
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INTERNATIONAL STANDARD ISO 21127:2023(E)
Information and documentation — A reference ontology
for the interchange of cultural heritage information
1 Scope
This document gives a curated, factual knowledge about the past at a human scale. It specifies all
information required for the exchange and integration of heterogeneous scientific and scholarly
documentation about the past at a human scale and the available documented and empirical evidence
4)
for this.
A more detailed and useful definition can be articulated by defining both the intended scope, a broad
and maximally-inclusive definition of general application principles, and the practical scope, which
is expressed by the overall scope of a growing reference set of specific, identifiable documentation
standards and practices that this document aims to semantically describe, restricted, always, in its
details to the limitations of the intended scope.
5)
The practical scope of this document is expressed in terms of the set of reference standards and
de facto standards for documenting factual knowledge. This document covers the same domain
of discourse as the union of these reference standards; this means that for data correctly encoded
according to these documentation formats there can be an ISO 21127-compatible expression that
conveys the same meaning.
2 Normative references
There are no normative references in this document.
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/
4) Annex A elaborates on this definition.
5) The practical scope of ISO 21127, including a list of the relevant museum documentation standards, is discussed
in more detail on the CIDOC CRM website at < https:// cidoc -crm .org/ scope .html >.
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ISO 21127:2023(E)
3.1
class
category of items that share one or more common traits serving as criteria to identify the items
belonging to the class
Note 1 to entry: These properties need not be explicitly formulated in logical terms, but may be described in a
text (here called a scope note) that refers to a common conceptualisation of domain experts. The sum of these
traits is called the intension of the class. A class may be the domain or range of none, one or more properties
formally defined in a model. The formally defined properties need not be part of the intension of their domains
or ranges: such properties are optional. An item that belongs to a class is called an instance of this class. A class
is associated with an open set of real-life instances, known as the extension of the class. Here “open” is used in
the sense that it is generally beyond our capabilities to know all instances of a class in the world and indeed that
the future may bring new instances about at any time (Open World). Therefore, a class cannot be defined by
enumerating its instances. A class plays a role analogous to a grammatical noun, and can be completely defined
without reference to any other construct (unlike properties, which shall have an unambiguously defined domain
and range). In some contexts, the terms individual class, entity or node are used synonymously with class. For
example, “Person” is a class. To be a “Person” may actually be determined by DNA characteristics, but everyone
knows what a “Person” is. A “Person” may have the property of being a member of a “Group”, but it is not necessary
to be member of a “Group” in order to be a “Person”. It is impossible to know all the "Persons" of the past. There
will be more “Person” in the future.
3.2
complement
set of all instances of B that are not instances of A
Note 1 to entry: Formally, it is the set-theoretic difference of the extension of B minus the extension of A.
Compatible extensions of the CIDOC CRM should not declare any class with the intension of them being the
complement of one or more other classes. To do so will normally violate the desire to describe an Open World. For
example, for all possible cases of human gender, male should not be declared as the complement of female or vice
versa. What if someone is both or even of another kind?
3.3
disjoint
having no common instances (3.8) in any possible world
Note 1 to entry: Classes are disjoint if the intersection of their extensions is an empty set.
3.4
domain
class (3.1) for which a property is formally defined
Note 1 to entry: This means that instances of the property are applicable to instances of its domain class. A
property shall have exactly one domain, although the domain class may always contain instances for which the
property is not instantiated. The domain class is analogous to the grammatical subject of the phrase for which
the property is analogous to the verb. It is arbitrary which class is selected as the domain and which as the range,
just as the choice between active and passive voice in grammar is arbitrary. Property names in this document are
designed to be semantically meaningful and grammatically correct when read from domain to range. In addition,
the inverse property name, normally given in parentheses, is also designed to be semantically meaningful and
grammatically correct when read from range to domain.
3.5
endurant
entities which are wholly present at any time they are present
Note 1 to entry: See Reference [87], pp. 166-181.
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ISO 21127:2023(E)
3.6
extension
set of all real-life instances belonging to the class that fulfil the criteria of its intension (3.9)
Note 1 to entry: The extension of a class is “open” in the sense that it is generally beyond our capabilities to know
all instances of a class in the world and indeed that the future may bring new instances about at any time (Open
World). An information system may at any point in time refer to some instances of a class, which form a subset of
its extension.
3.7
inheritance
duplication of properties from a class to its subclasses
Note 1 to entry: Inheritance of properties from superclasses to subclasses means that if an item x is an instance
of a class A, then all properties that shall hold for the instances of any of the superclasses of A shall also hold for
item x, and that all optional properties that may hold for the instances of any of the superclasses of A may also
hold for item x.
3.8
instance
items having properties that meet the criteria of the intension (3.9) of the classes
Note 1 to entry: The number of instances declared for a class in an information system is typically less than
the total in the real world. For example, the reader is an instance of Person, but they are not mentioned in all
information systems describing Persons.
Note 2 to entry: For example, the painting known as the “The Mona Lisa” is an instance of the class E22 Human-
Made Object. An instance of a property is a factual relation between an instance of the domain and an instance of
the range of the property that matches the criteria of the intension of the property. For example, “The Mona Lisa”
has former or current owner. The Louvre is an instance of the property P51 has former or current owner (is former
or current owner of).
3.9
intension
intended meaning of a class
Note 1 to entry: The intension of a class consists of one or more common traits shared by all instances of the class
or property. These traits need not be explicitly formulated in logical terms, but may just be described in a text
(here called a scope note) that refers to a conceptualisation common to domain experts.
3.10
interoperability
capability of different information systems to communicate some of their contents
Note 1 to entry: Interoperability may mean that two systems can exchange information, and/or that multiple
systems can be accessed with a single method.
Note 2 to entry: Generally, syntactic interoperability is distinguished from semantic interoperability. Syntactic
interoperability means that the information encoding of the involved systems and the access protocols are
compatible, so that information can be processed as described above without error. However, this does not mean
that each system processes the data in a manner consistent with the intended meaning. For example, one system
may use a table called “Actor” and another one called “Agent”. With syntactic interoperability, data from both
tables may only be retrieved as distinct, even though they may have exactly the same meaning. To overcome this
situation, semantic interoperability has to be added. This document relies on existing syntactic interoperability
and is concerned only with adding semantic interoperability (3.24).
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ISO 21127:2023(E)
3.11
inverse of
reinterpretation of a property from range to domain without more general or more specific meaning
Note 1 to entry: The inverse of a property is similar to the choice between active and passive voice in some
languages. In contrast to some knowledge representation languages, such as RDF and OWL, this document
regards that the inverse of a property is not a property in its own right that needs an explicit declaration of
being inverse of another, but an interpretation implicitly existing for any property. The inverse of the inverse of
a property is identical to the property itself, i.e. its primary sense of direction. For example, “Entity is depicted by
Physical Human-Made Thing” is the inverse of “Physical Human-Made Thing depicts Entity”.
3.12
knowledge creation event
organized transfer of knowledge of a group of domain experts into an information system under
preservation of the relationship between those regarding the created content as representing their
knowledge and the knowledge itself
Note 1 to entry: All knowledge contained in an information system must have been introduced into that system
by some human agent, either directly or indirectly. Despite this fact, many, if not most, statements within such a
system will lack specific attribution of authority. That being said, in the domain of cultural heritage, it is common
practice that, for the processes of collection documentation and management, there are clearly and explicitly
elaborated systems of responsibility outlining by whom and how knowledge can be added and or modified in the
system. Ideally these systems are specified in institutional policy and protocol documents. Thus, it is reasonable
to hold that all such statements that lack explicit authority attribution within the information system can, in
fact, be read as the official view of the administrating institution of that system. Such a position does not mean
to imply that an information system represents at any particular moment a completed phase of knowledge that
the institution promotes. Rather, it means to underline that, in a CH context, a managed set of data, at any state
of elaboration, will in fact embody an adherence to some explicit code of standards which guarantees the validity
of that data within the scope of said standards and all practical limitations. So long as the information is under
active management it remains continuously open to revision and improvement as further research reveals
further understanding surrounding the objects of concern. A distinct exception to this rule is represented by
information in the data set that carries with it an explicit statement of responsibility.
Note 2 to entry: In this document, such statements of responsibility are expressed through knowledge creation
events such as E13 Attribute Assignment and its relevant subclasses. Any information in a model using this
document that is based on an explicit creation event for that piece of information, where the creator’s identity
has been given, is attributed to the authority and assigned to the responsibility of the actor identified as causal
in that event. For any information in the system connected to knowledge creation events that do not explicitly
reference their creator, as well as any information not connected to creation events, the responsibility falls back
to the institution responsible for the database/knowledge graph. That means that for information only expressed
through shortcuts such as P2 has type, where no knowledge creation event has been explicitly specified, the
originating creation event cannot be deduced and the responsibility for the information can never be any other
body than the institution responsible for the whole information system. In the case of an institution taking over
stewardship of a database transferred into their custody, two relations of responsibility for the knowledge
therein can be envisioned. If the institution accepts the dataset and undertakes to maintain and update it, then
they take on responsibility for that information and become the default authority behind
...
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