ISO/IEC/IEEE FDIS 21841

• Abstract:

  This document defines a normalized taxonomy for systems of systems (SoS) to facilitate communications among stakeholders. It also briefly explains what a taxonomy is and how it applies to the SoS to aid in understanding and communication.

• Status: Not Published
• ICS: 35.080 - Software
• Technical Committee: ISO/IEC JTC 1/SC 7 - Software and systems engineering
• Drafting Committee: ISO/IEC JTC 1/SC 7/WG 7 - Life cycle management
• Current Stage: 5060 - Close of voting Proof returned by Secretariat
• Start Date: 17-Jun-2026
• Completion Date: 16-Jun-2026

• Revises: ISO/IEC/IEEE 21841:2019 - Systems and software engineering — Taxonomy of systems of systems
• Effective Date: 07-Jan-2025

Overview

ISO/IEC/IEEE FDIS 21841: Systems and Software Engineering - Taxonomy of Systems of Systems establishes a standardized taxonomy for systems of systems (SoS). The document provides a clear classification framework to enable effective communication, understanding, and collaboration among diverse stakeholders in complex SoS environments. By defining key concepts and categorizing SoS types based on their structural and operational characteristics, ISO/IEC/IEEE 21841 supports improved systems engineering, governance, and lifecycle management.

A taxonomy, as referenced in the standard, is a structured scheme that partitions a body of knowledge and defines relationships among its elements. For SoS, this approach clarifies distinctions between traditional systems and systems composed of independent yet interconnected constituent systems. The taxonomy outlined in ISO/IEC/IEEE 21841 helps organizations consistently describe, analyze, and manage systems of systems in various domains.

Key Topics

• Definitions and Terminology: The standard precisely defines terms such as system, constituent system (CS), system of systems (SoS), and systems of systems engineering (SoSE), providing a common foundation for practitioners.
• Core Taxonomy: SoS are classified into four principal types:
  • Directed: SoS where all constituent systems operate under a central authority toward a specific purpose.
  • Acknowledged: SoS with a recognized manager and resources; constituent systems retain operational independence but coordinate through agreements.
  • Collaborative: SoS where constituent systems voluntarily interact for common goals, with no central control.
  • Virtual: SoS lacking central management or agreed purpose; large-scale behaviors emerge from loosely coupled systems.
• Importance of Taxonomies: The document discusses how taxonomies streamline stakeholder communication and decision-making throughout the SoS lifecycle.
• Criteria for Taxonomy Selection: Stability, public availability of external references, and proven application in multiple systems are emphasized for selecting a robust taxonomy.

Applications

ISO/IEC/IEEE 21841 is relevant wherever complex systems integrating multiple independent elements are engineered, managed, or maintained. Practical applications include:

• Smart Cities: Classification helps urban planners align capabilities, objectives, and governance across departments and independently managed infrastructure systems.
• Transportation Networks: The taxonomy assists in distinguishing between managed, collaborative, and emergent behaviors in intelligent transport SoS, such as real-time route optimization platforms.
• Defense Systems: Identification of directed or collaborative SoS structures supports the integration and management of military command, control, and communication systems.
• Digital Ecosystems & the Internet: Collaborative models apply to networks and digital platforms governed by open standards and peer coordination rather than centralized authority.

By adopting ISO/IEC/IEEE 21841, organizations can:

• Facilitate clearer communication among stakeholders with varying perspectives.
• Choose fitting approaches for SoS engineering, operations, and lifecycle management.
• Address stakeholder concerns relating to governance, ownership, and resource allocation.
• Support compliance with industry regulations or sector-specific standards referencing systems of systems.

Related Standards

ISO/IEC/IEEE FDIS 21841 is aligned with and complements several foundational documents in systems and software engineering:

• ISO/IEC/IEEE 15288: Systems and software engineering - System life cycle processes
• ISO/IEC/IEEE 21840: Guidelines for the utilization of ISO/IEC/IEEE 15288 in the context of system of systems
• ISO/IEC 19770-1: IT asset management
• ISO/IEC/IEEE 24765: Systems and software engineering vocabulary
• ISO/IEC/IEEE 26531: Content management for product life cycle, user and service management information

These related standards together enhance the practical value of ISO/IEC/IEEE 21841, supporting a comprehensive approach to systems of systems engineering, terminology, and lifecycle management.

Keywords: systems of systems, SoS taxonomy, systems engineering, constituent systems, ISO/IEC/IEEE 21841, SoSE, governance, collaborative systems, acknowledged systems, directed systems, virtual systems, stakeholder communication, system lifecycle

DRAFT
International
Standard
ISO/IEC/IEEE
DIS
ISO/IEC JTC 1/SC 7
Systems and software
Secretariat: BIS
engineering — Taxonomy of
Voting begins on:
systems of systems
2025-09-10
Ingénierie système et logiciel — Taxonomie des systèmes de
Voting terminates on:
systèmes
2025-12-03
ICS: 35.080
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
This document has not been edited by the ISO Central Secretariat.
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Reference number
© ISO/IEC 2025
ISO/IEC/IEEE DIS 21841:2025(en)
© IEEE 2025
DRAFT
ISO/IEC/IEEE DIS 21841:2025(en)
International
Standard
ISO/IEC/IEEE
DIS
ISO/IEC JTC 1/SC 7
Systems and software
Secretariat: BIS
engineering — Taxonomy of
Voting begins on:
systems of systems
Ingénierie système et logiciel — Taxonomie des systèmes de
Voting terminates on:
systèmes
ICS: 35.080
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
© ISO/IEC 2025
BEING ACCEPTABLE FOR INDUSTRIAL,
© IEEE 2025
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
This document has not been edited by the ISO Central Secretariat. BE CONSIDERED IN THE LIGHT OF THEIR
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO or IEEE at the
POTENTIAL TO BECOME STANDARDS TO
respective address below or ISO’s member body in the country of the requester.
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
ISO copyright office Institute of Electrical and Electronics Engineers, Inc
CP 401 • Ch. de Blandonnet 8 3 Park Avenue, New York RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
CH-1214 Vernier, Geneva NY 10016-5997, USA
NOTIFICATION OF ANY RELEVANT PATENT
Phone: [phone]
RIGHTS OF WHICH THEY ARE AWARE AND TO
Email: [e-mail] Email: [e-mail]
PROVIDE SUPPORTING DOCUMENTATION.
Website: www.iso.org Website: www.ieee.org
Published in Switzerland
Reference number
© ISO/IEC 2025
ISO/IEC/IEEE DIS 21841:2025(en)
© IEEE 2025
© ISO/IEC 2025, © IEEE 2025 – All rights reserved
ii
ISO/IEC/IEEE DIS 21841:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 1
3.1 General terms .1
3.2 SoS types .3
3.3 Abbreviated terms .3
4 Concepts and application . 4
4.1 Overview .4
4.2 Importance of taxonomies to SoS .4
4.3 Use of SoS taxonomies.4
5 Taxonomies for systems of systems . 4
5.1 General .4
5.2 Taxonomy: directed, acknowledged, collaborative and virtual .5
5.2.1 Overview .5
5.2.2 Description of the taxa .5
5.2.3 Examples of potential application of the taxonomy .6
5.2.4 When to use .6
5.2.5 How to use .6
5.2.6 Why to use.6
5.2.7 Limitations .6
5.2.8 Benefits of use .7
Annex A (informative) Summary of SoS taxonomies . 8
Bibliography . 9

© ISO/IEC 2025, © IEEE 2025 – All rights reserved
iii
ISO/IEC/IEEE DIS 21841:2025(en)
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 ISO documents should be noted. This document was drafted in accordance with the rules given in the ISO/
IEC Directives, Part 2 (see www.iso.org/directives).
IEEE Standards documents are developed within IEEE Societies and subcommittees of IEEE Standards
Association (IEEE SA) Board of Governors. IEEE develops its standards through an accredited consensus
development process, which brings together volunteers representing varied viewpoints and interests to
achieve the final product. IEEE standards are documents developed by volunteers with scientific, academic,
and industry-based expertise in technical working groups. Volunteers are not necessarily members of
IEEE or IEEE SA and participate without compensation from IEEE. While IEEE administers the process and
establishes rules to promote fairness in the consensus development process, IEEE does not independently
evaluate, test, or verify the accuracy of any of the information or the soundness of any judgments contained
in its standards.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC 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) or the IEC list of patent declarations
received (see http://patents.iec.ch).
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 Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 7, Systems and software engineering, in cooperation with the Systems and Software
Engineering Standards Committee of IEEE Computer Society, under the Partner Standards Development
Organization cooperation agreement between ISO and IEEE.
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.
This second edition cancels and replaces the first edition (ISO/IEC/IEEE 21841:2019) which has been
technically revised to include updates to definitions.

© ISO/IEC 2025, © IEEE 2025 – All rights reserved
iv
ISO/IEC/IEEE DIS 21841:2025(en)
Introduction
Systems of systems engineering (SoSE) is a concept that is increasingly thought of as a discipline important
for the realization and sustainability of large and persistent sociotechnical systems in areas as diverse as
healthcare, transportation, energy, defence, corporations, cities and government.
While SoSE applies broadly to hardware, software, middle-ware as well as embedded, cyber-physical and
digital systems, the importance of SoSE has been heightened in the last fifteen years by the rapid increase
in the pervasiveness of information technology (IT), illustrated by new technologies and paradigms such as
Sensor Networks, Cloud Computing, the Internet of Things, Big Data, Smart Devices and Artificial Intelligence.
It is, for instance, the application of these technologies to cities that transform them into “smarter” cities.
This pervasiveness of IT was not only driven by the availability of these technologies, but also more
importantly by the requirements in our resource and environmentally-constrained world for increased and
sustainable economic development and, ultimately, personal well-being.
SoSE goes well beyond IT and potentially applies to all types of systems, including hardware and cyber
physical systems where IT is an enabler. SoSE addresses functionality, performance and interdependencies
of the systems as well as their connectivity. The interconnectivity of systems has become pervasive in large
command and control systems, defence systems, communications systems, transportation systems and
medical/health systems, among others. The accelerating need to share information and leverage capabilities
from other systems has changed how systems need to be viewed and engineered.
Taxonomies provide a means in many fields to classify and describe the relationships among the relevant
elements being studied. The elements of a taxonomy, individually called a taxon or collectively called taxa,
form a partitioning or means of classification within that body of knowledge. In the context of systems
of systems (SoS), the relevant elements of the system of interest are, by definition, systems themselves.
Using essential characteristics to partition the various types of SoS provides an abbreviated nomenclature
for thinking about SoS. Based on taxonomies, different approaches to the engineering of SoS are possible,
improving the efficiency and effectiveness of SoSE.

© ISO/IEC 2025, © IEEE 2025 – All rights reserved
v
DRAFT International Standard ISO/IEC/IEEE DIS 21841:2025(en)
Systems and software engineering — Taxonomy of systems
of systems
1 Scope
This document defines a normalized taxonomy for systems of systems (SoS) to facilitate communications
among stakeholders. It also briefly explains what a taxonomy is and how it applies to the SoS to aid in
understanding and communication.
2 Normative references
There are no normative references in this document.
3 Terms, definitions and abbreviated terms
For the purposes of this document, the following terms and definitions apply.
ISO, IEC, and IEEE maintain terminological 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/
— IEEE Standards Dictionary Online: available at http:// dictionary .ieee .org
NOTE For additional terms and definitions in the field of systems and software engineering, see
ISO/IEC/IEEE 24765, which is published periodically as a “snapshot” of the SEVOCAB (Systems and software
Engineering Vocabulary) database and is publicly accessible at www .computer .org/ sevocab.
3.1 General terms
3.1.1
capability
measure of capacity and the ability of an entity (system (3.1.5)), person or organization) to achieve its
objectives
[SOURCE: ISO/IEC 19770-1:2017, 3.10, modified - Note 1 to entry has been removed.]
3.1.2
constituent system
CS
independent system (3.1.5) that forms part of a system of systems (3.1.6) (SoS)
Note 1 to entry: Constituent systems can be part of one or more SoS. Each CS (3.1.2) is a useful system (3.1.5) by
itself, having its own development, management (3.1.4), utilization, goals, and resources, but interacts within the SoS
to provide the unique capability (3.1.1) of the SoS.
Note 2 to entry: While CS operate independently from each other for their own purposes, they also operate
interdependently with each other and other elements to produce the SoS outputs. CS are never totally independent, since
they work interdependently when operating as part of the SoS. However, they are never totally subservient to the SoS.
Because CS have their own stakeholders and CS remain managerially independent, CS managers generally are not
motivated to make adjustments to address SoS-desired capabilities.
[SOURCE: ISO/IEC/IEEE 21840:2025, 3.1.2]

© ISO/IEC 2025, © IEEE 2025 – All rights reserved
ISO/IEC/IEEE DIS 21841:2025(en)
3.1.3
governance
process of establishing and enforcing strategic goals and objectives, organizational policies and performance
parameters
[SOURCE: ISO/IEC/IEEE 21840:2025, 3.1.4]
3.1.4
management
system of controls and processes required to achieve the strategic objectives set by the organization's
governing body
Note 1 to entry: Management is subject to the policy guidance and monitoring set through corporate governance
(3.1.3).
[SOURCE: ISO/IEC/IEEE 21840:2025, 3.1.5]
3.1.5
system
arrangement of parts or elements that together exhibit a stated behaviour or meaning that the individual
constituents do no
...

FINAL DRAFT
International
Standard
ISO/IEC/IEEE
FDIS
ISO/IEC JTC 1/SC 7
Systems and software
Secretariat: BIS
engineering — Taxonomy of
Voting begins on:
systems of systems
2026-04-21
Ingénierie système et logiciel — Taxonomie des systèmes de
Voting terminates on:
systèmes
2026-06-16
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number © ISO/IEC 2026
FINAL DRAFT
International
Standard
ISO/IEC/IEEE
FDIS
ISO/IEC JTC 1/SC 7
Systems and software
Secretariat: BIS
engineering — Taxonomy of
Voting begins on:
systems of systems
Ingénierie système et logiciel — Taxonomie des systèmes de
Voting terminates on:
systèmes
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
© ISO/IEC 2026
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© IEEE 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO or IEEE at the INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
respective address below or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
ISO copyright office Institute of Electrical and Electronics Engineers, Inc MADE IN NATIONAL REGULATIONS.
CP 401 • Ch. de Blandonnet 8 3 Park Avenue, New York
CH-1214 Vernier, Geneva NY 10016-5997, USA
Phone: [phone]
Email: [e-mail] Email: [e-mail]
Website: www.iso.org Website: www.ieee.org
Published in Switzerland
Reference number © ISO/IEC 2026
© ISO/IEC 2026, © IEEE 2026 – All rights reserved
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms .1
3.2 SoS types .3
4 Concepts and application . 4
4.1 Overview .4
4.2 Importance of taxonomies to SoS .4
4.3 Use of SoS taxonomies.5
5 Taxonomies for systems of systems
............................................................................................................................................................ 5
5.1 General .5
5.2 Taxonomy: directed, acknowledged, collaborative and virtual .5
5.2.1 Overview .5
5.2.2 Description of the taxa .5
5.2.3 Examples of potential application of the taxonomy .6
5.2.4 When to use .6
5.2.5 How to use .7
5.2.6 Why to use.7
5.2.7 Limitations .7
5.2.8 Benefits of use .7
Annex A (informative) Summary of SoS taxonomies . 8
Bibliography . 9
IEEE notices and abstract . 10

© ISO/IEC 2026, © IEEE 2026 – 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).
IEEE Standards documents are developed within IEEE Societies and subcommittees of IEEE Standards
Association (IEEE SA) Board of Governors. IEEE develops its standards through an accredited consensus
development process, which brings together volunteers representing varied viewpoints and interests to
achieve the final product. IEEE standards are documents developed by volunteers with scientific, academic,
and industry-based expertise in technical working groups. Volunteers are not necessarily members of
IEEE or IEEE SA and participate without compensation from IEEE. While IEEE administers the process and
establishes rules to promote fairness in the consensus development process, IEEE does not independently
evaluate, test, or verify the accuracy of any of the information or the soundness of any judgments contained
in its standards.
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 Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 7, Systems and software engineering, in cooperation with the Systems and Software
Engineering Standards Committee of IEEE Computer Society, under the Partner Standards Development
Organization cooperation agreement between ISO and IEEE.
This second edition cancels and replaces the first edition (ISO/IEC/IEEE 21841:2019) which has been
technically revised.
The main changes are as follows:
— the text has been updated to be aligned with ISO/IEC/IEEE 15288:2023 and ISO/IEC/IEEE 21840.
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.

© ISO/IEC 2026, © IEEE 2026 – All rights reserved
iv
Introduction
Systems of systems engineering (SoSE) is a concept that is increasingly thought of as a discipline important
for the realization and sustainability of large and persistent sociotechnical systems in areas as diverse as
healthcare, transportation, energy, defence, corporations, cities and government.
While SoSE applies broadly to hardware, software, and middleware as well as embedded, cyber-physical and
digital systems, the importance of SoSE has been heightened in the last fifteen years by the rapid increase
in the pervasiveness of information technology (IT), illustrated by new technologies and paradigms such as
sensor networks, cloud computing, the internet of things, big data, smart devices and artificial intelligence.
It is, for instance, the application of these technologies to cities that transform them into smarter cities.
This pervasiveness of IT was not only driven by the availability of these technologies, but also more
importantly by the requirements in our resource and environmentally-constrained world for increased and
sustainable economic development and, ultimately, personal well-being.
SoSE goes well beyond IT and potentially applies to all types of systems, including hardware and cyber
physical systems where IT is an enabler. SoSE addresses functionality, performance and interdependencies
of the systems as well as their connectivity. The interconnectivity of systems has become pervasive in large
command and control systems, defence systems, communications systems, transportation systems and
medical/health systems, among others. The accelerating need to share information and leverage capabilities
from other systems has changed how systems need to be viewed and engineered.
In the context of systems of systems (SoS), the relevant elements of the system of interest are, by definition,
systems themselves. Using essential characteristics to partition the various types of SoS provides an
abbreviated nomenclature for thinking about SoS. Based on taxonomies, different approaches to the
engineering of SoS are possible, improving the effectiveness and efficiency of SoSE.

© ISO/IEC 2026, © IEEE 2026 – All rights reserved
v
FINAL DRAFT International Standard ISO/IEC/IEEE FDIS 21841:2026(en)
Systems and software engineering — Taxonomy of systems of
systems
1 Scope
This document defines a normalized taxonomy for systems of systems (SoS) to facilitate communications
among stakeholders. It also briefly explains what a taxonomy is and how it applies to the SoS to aid in
understanding and communication.
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, IEC, and IEEE 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/
— IEEE Standards Dictionary Online: available at http:// dictionary .ieee .org
NOTE For additional terms and definitions in the field of systems and software engineering, see
ISO/IEC/IEEE 24765, which is published periodically as a “snapshot” of the SEVOCAB (Systems and software
Engineering Vocabulary) database and is publicly accessible at www .computer .org/ sevocab.
3.1 General terms
3.1.1
capability
measure of capacity and the ability of an entity (system (3.1.7)), person or organization (3.1.6)) to achieve its
objectives
[SOURCE: ISO/IEC 19770-1:2017, 3.10, modified - Note 1 to entry has been removed.]
3.1.2
constituent system
CS
independent system (3.1.7) that forms part of a system of systems (3.1.9) (SoS)
Note 1 to entry: Constituent systems can be part of one or more SoS. Each CS is a useful system by itself, having its own
development, management (3.1.5), utilization, goals, and resources, but interacts within the SoS to provide the unique
capability (3.1.1) of the SoS.
Note 2 to entry: While CS operate independently from each other for their own purposes, they also operate
interdependently with each other and other system elements (3.1.8) to produce the SoS outputs. CS are never totally
independent, since they work interdependently when operating as part of the SoS. However, they are never totally
subservient to the SoS. CS have their own stakeholders and CS remain managerially and operationally independent;
managers of CS or CS projects can be unaware, unable or unwilling to make adjustments to address SoS-desired
capabilities (3.1.1)
© ISO/IEC 2026, © IEEE 2026 – All rights reserved
[SOURCE: ISO/IEC/IEEE 21840:—, 3.1.2]
3.1.3
governance
practice of establishing and enforcing strategic goals and objectives, organizational policies and performance
parameters
[SOURCE: ISO/IEC/IEEE 12207: —, 3.1.28]
3.1.4
interoperating system
system (3.1.7) that exchanges information with the system of interest (3.1.11) and uses the information that
has been exchanged
[SOURCE: ISO/IEC/IEEE 15288:2023, 3.20]
3.1.5
management
system (3.1.7) of controls and processes required to achieve the strategic objectives set by the organization's
(3.1.6) governing body
Note 1 to entry: Management is subject to the policy guidance and monitoring set through corporate governance
(3.1.3).
[SOURCE: ISO/IEC/IEEE 21840: —, 3.1.6]
3.1.6
organization
person or group of people that has its own functions with responsibilities, authorities, and relationships to
achieve its objectives
EXAMPLE Company, corporation, firm, enterprise, manufacturer, institution, charity, sole trader, association, or
parts or combination thereof.
[SOURCE: ISO/IEC/IEEE 9000:2015, 3.2.1, modified — Notes to entry have been removed; EXAMPLE has
been added.]
3.1.7
system
arrangement of parts or elements that together exhibit a stated behaviour or meaning that the individual
constituents do not
Note 1 to entry: A system is sometimes considered as a product or as the services it provides.
Note 2 to entry: In practice, the interpretation of its meaning is frequently clarified by the use of an associative noun,
e.g. aircraft system. Alternatively, the word “system” is substituted simply by a context-dependent synonym (e.g.
aircraft), though this potentially obscures a system principles perspective.
Note 3 to entry: A complete system includes all of the associated equipment, facilities, material, computer programs,
firmware, technical documentation, services, and personnel required for operations and support to the degree
necessary for self-sufficient use in its intended environment.
[SOURCE: ISO/IEC/IEEE 15288:2023, 3.46]
3.1.8
system element
discrete part of a system (3.1.7) that can be implemented to fulfil specified requirements
EXAMPLE Hardware, software, data, humans, processes [e.g. processes for providing service to users, procedures
[e.g., operator instructions], facilities, materials, and naturally occurring entities or any combination.
[SOURCE: ISO/IEC/IEEE 15288:2023, 3.47]

© ISO/IEC 2026, © IEEE 2026 – All rights reserved
3.1.9
system of systems
SoS
set of systems (3.1.7) and systemelements (3.1.8) that interact to provide a unique capability (3.1.1) that none
of the constituent systems (3.1.2) can accomplish on its own
Note 1 to entry: System elements can be necessary to facilitate interaction of the constituent systems in the SoS.
Note 2 to entry: A collection of systems is not always an SoS. The differences between a system and an SoS are not
in the structure of the parts, but rather in the managerial and operational independence of those parts. There is no
distinct boundary that separates systems from SoS, as the transition between the two is often gradual and context
dependent.
[SOURCE: ISO/IEC/IEEE 21840: —, 3.1.11]
3.1.10
system of systems engineering
SoSE
process of planning, analysing, organizing, developing and integrating the capabilities (3.1.1) of a mix of
existing and new systems (3.1.7), including inter-system infrastructure, facilities, and overarching processes
into a system of systems (3.1.9) capability that is greater than the sum of the capabilities of the constituent
systems (3.1.2)
Note 1 to entry: SoSE also includes testing, modification, maintenance and other post-integration activities.
[SOURCE: ISO/IEC/IEEE 21840: —, 3.1.12]
3.1.11
system of interest
SoI
system (3.1.7) whose life cycle is under consideration
[SOURCE: ISO/IEC/IEEE15288: 2023, 3.48]
3.1.12
systems engineering
transdisciplinary and integrative approach to enable the successful realization, use, and retirement
of engineered systems (3.1.7) using systems principles and concepts and scientific, technological and
management (3.1.5) methods
[SOURCE: INCOSE-TP-2020-002-06]
3.1.13
taxonomy
scheme that partitions a body of knowledge and defines the relationships among the parts
[SOURCE: ISO/IEC/IEEE 26531:2023, 3.1.30]
3.2 SoS types
3.2.1
acknowledged SoS
acknowledged system of systems
SoS (3.1.10) with recognized objectives, a designated manager, and resources
Note 1 to entry: Constituent systems (3.1.2) retain their independent ownership, objectives, funding, and development
and sustainment approaches. Changes in the systems are based on cooperative agreements between the managers of
the SoS and the managers of the CS.
[SOURCE: ISO/IEC/IEEE 21840:—, 3.2.1]

© ISO/IEC 2026, © IEEE 2026 – All rights reserved
3.2.2
collaborative SoS
collaborative system of systems
SoS (3.1.10) in which constituent systems (CS) (3.1.2) operationally interact more or less voluntarily to fulfil
agreed-upon central purposes
Note 1 to entry: Managers of CS or CS projects collaboratively decide how to provide or deny service, thereby providing
means of enforcing and maintaining consistency.
[SOURCE: ISO/IEC/IEEE 21840: —, 3.2.2]
3.2.3
directed SoS
directed system of systems
SoS (3.1.10) created and managed to fulfil specific purposes, with constituent systems (3.1.2) that are
subordinated to the SoS
Note 1 to entry: Constituent systems maintain an ability to operate independently; however, their normal operational
mode is subordinated to the central managed purpose.
[SOURCE: ISO/IEC/IEEE 21840: —, 3.2.3]
3.2.4
virtual SoS
virtual system of systems
SoS (3.1.10) that lacks a central management (3.1.5) authority and a centrally-agreed-upon purpose
Note 1 to entry: Large-scale behaviour emerges—and can be desirable—but this type of SoS relies on relatively
invisible mechanisms to maintain it.
Note 2 to entry: Virtual SoS are typically self-organizing.
[SOURCE: ISO/IEC/IEEE 21840: — 3.2.4]
4 Concepts and application
4.1 Overview
Taxonomies provide a means in many fields to classify and describe the relationships between the relevant
elements being studied. The elements of a taxonomy, individually called a taxon or collectively called taxa,
form a partitioning or means of classification within that body of knowledge. Partitioning based on essential
characteristics provides an abbreviated nomenclature to refer to a larger composite of characteristics,
facilitating discussion about the partitions (taxa) without having to refer to each of the characteristics.
4.2 Importance of taxonomies to SoS
In systems engineering (SE), the relevant pieces of the system of interest (SoI) can be system elements or
components. In the context of SoS, the relevant pieces of the SoI are, by definition, systems themselves. These
are called constituent systems (CS) throughout this document. That is, an SoS consists of some number of
CS, plus any inter-system infrastructure, facilities and processes necessary to enable the CS to integrate or
interoperate. Relationships between CS affect the SoS. Using essential characteristics to partition the various
types of SoS provides an abbreviated nomenclature for thinking about SoS. While Clause 5 elaborates one
mature SoS taxonomy, Annex A provides a list of SoS less-mature taxonomies. Based on taxonomies, different
approaches to the engineering of systems of systems are possible, improving the efficiency and effectiveness
of SoSE.
NOTE 1 Taxonomies can have some overlap in their de
...

ISO/IEC JTC 1/SC 7 N10069
Secretariat: BIS
Date: 2026-01-1204-07
Systems and software engineering — Taxonomy of systems of
systems
Ingénierie système et logiciel — Taxonomie des systèmes de systèmes
FDIS stage
© ISO/IEC/IEEE 2026
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
or IEEE at the respective address below or ISO’s member body in the country of the requester.
ISO copyright office  Institute of Electrical and Electronics Engineers, Inc
CP 401 • Ch. de Blandonnet 8  3 Park Avenue, New York
CH-1214 Vernier, Geneva  NY 10016-5997, USA
Phone: + 41 22 749 01 11
E-mail: [e-mail]  Email: [e-mail]
Website: www.iso.org  Website:
Published in Switzerland
© ISO/IEC/IEEE 2026 – All rights reserved
ii
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms . 1
3.2 SoS types . 4
4 Concepts and application . 4
4.1 Overview . 4
4.2 Importance of taxonomies to SoS . 5
4.3 Use of SoS taxonomies . 5
5 Taxonomies for systems of systems . 5
5.1 General . 5
5.2 Taxonomy: directed, acknowledged, collaborative and virtual . 5
Annex A (informative) Summary of SoS taxonomies . 9
Bibliography . 10
IEEE notices and abstract . 11

© ISO/IEC/IEEE 2026 – 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
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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).
IEEE Standards documents are developed within IEEE Societies and subcommittees of IEEE Standards
Association (IEEE SA) Board of Governors. IEEE develops its standards through an accredited consensus
development process, which brings together volunteers representing varied viewpoints and interests to
achieve the final product. IEEE standards are documents developed by volunteers with scientific, academic,
and industry-based expertise in technical working groups. Volunteers are not necessarily members of IEEE or
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or verify the accuracy of any of the information or the soundness of any judgments contained in its standards.
ISO and IEC draw attention to the possibility that the implementation of this document may involve the use of
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Any trade name used in this document is information given for the convenience of users and does not
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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 Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 7, Systems and software engineering, in cooperation with the Systems and Software
Engineering Standards Committee of IEEE Computer Society, under the Partner Standards Development
Organization cooperation agreement between ISO and IEEE.
This second edition cancels and replaces the first edition (ISO/IEC/IEEE 21841:2019) which has been
technically revised.
The main changes are as follows:
— — the text has been updated to be aligned with ISO/IEC/IEEE 15288:2023 and ISO/IEC/IEEE 21840:2026.
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.
© ISO/IEC/IEEE 2026 – All rights reserved
iv
Introduction
Systems of systems engineering (SoSE) is a concept that is increasingly thought of as a discipline important
for the realization and sustainability of large and persistent sociotechnical systems in areas as diverse as
healthcare, transportation, energy, defence, corporations, cities and government.
While SoSE applies broadly to hardware, software, and middleware as well as embedded, cyber-physical and
digital systems, the importance of SoSE has been heightened in the last fifteen years by the rapid increase in
the pervasiveness of information technology (IT), illustrated by new technologies and paradigms such as
sensor networks, cloud computing, the internet of things, big data, smart devices and artificial intelligence. It
is, for instance, the application of these technologies to cities that transform them into smarter cities.
This pervasiveness of IT was not only driven by the availability of these technologies, but also more
importantly by the requirements in our resource and environmentally-constrained world for increased and
sustainable economic development and, ultimately, personal well-being.
SoSE goes well beyond IT and potentially applies to all types of systems, including hardware and cyber
physical systems where IT is an enabler. SoSE addresses functionality, performance and interdependencies of
the systems as well as their connectivity. The interconnectivity of systems has become pervasive in large
command and control systems, defence systems, communications systems, transportation systems and
medical/health systems, among others. The accelerating need to share information and leverage capabilities
from other systems has changed how systems need to be viewed and engineered.
In the context of systems of systems (SoS), the relevant elements of the system -of -interest are, by definition,
systems themselves. Using essential characteristics to partition the various types of SoS provides an
abbreviated nomenclature for thinking about SoS. Based on taxonomies, different approaches to the
engineering of SoS are possible, improving the effectiveness and efficiency of SoSE.
© ISO/IEC/IEEE 2026 – All rights reserved
v
Systems and software engineering — Taxonomy of systems of systems
1 Scope
This document defines a normalized taxonomy for systems of systems (SoS) to facilitate communications
among stakeholders. It also briefly explains what a taxonomy is and how it applies to the SoS to aid in
understanding and communication.
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, IEC, and IEEE 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/
— IEEE Standards Dictionary Online: available at http://dictionary.ieee.org
NOTE For additional terms and definitions in the field of systems and software engineering, see
ISO/IEC/IEEE 24765, which is published periodically as a “snapshot” of the SEVOCAB (Systems and software Engineering
Vocabulary) database and is publicly accessible at www.computer.org/sevocab.
3.1 General terms
3.1.1
capability
measure of capacity and the ability of an entity (system (3.1.(3.1.7)), person or organization (3.1.6(3.1.6)))) to
achieve its objectives
[SOURCE: ISO/IEC 19770-1:2017, 3.10, modified - Note 1 to entry has been removed.]
3.1.2
constituent system
CS
independent system ((3.1.7) that forms part of a system of systems (3.1.9(3.1.9)) (SoS)
Note 1 to entry: Constituent systems can be part of one or more SoS. Each CS is a useful system by itself, having its own
development, management ((3.1.5), utilization, goals, and resources, but interacts within the SoS to provide the unique
capability (3.1.1()) of the SoS.
Note 2 to entry: While CS operate independently from each other for their own purposes, they also operate
interdependently with each other and other system elements (3.1.8(3.1.8)) to produce the SoS outputs. CS are never
totally independent, since they work interdependently when operating as part of the SoS. However, they are never totally
subservient to the SoS. CS have their own stakeholders and CS remain managerially and operationally independent;
managers of CS or CS projects can be unaware, unable or unwilling to make adjustments to address SoS-desired
capabilities (3.1.1(3.1.1))
[SOURCE: ISO/IEC/IEEE 21840:2026,:—, 3.1.2]
© ISO/IEC/IEEE 2026 – All rights reserved
3.1.3
governance
practice of establishing and enforcing strategic goals and objectives, organizational policies and performance
parameters
[SOURCE: ISO/IEC/IEEE 12207:2026, —, 3.1.28]
3.1.4
interoperating system
system (3.1.7(3.1.7)) that exchanges information with the system -of -interest (3.1.11(3.1.11)) and uses the
information that has been exchanged
[SOURCE: ISO/IEC/IEEE 15288:2023, 3.20]
3.1.5
management
system (3.1.7(3.1.7)) of controls and processes required to achieve the strategic objectives set by the
organization's (3.1.6(3.1.6)) governing body
Note 1 to entry: Management is subject to the policy guidance and monitoring set through corporate governance
(3.1.3().).
[SOURCE: ISO/IEC/IEEE 21840:2026, —, 3.1.76]
3.1.6
organization
person or group of people that has its own functions with responsibilities, authorities, and relationships to
achieve its objectives
EXAMPLE Company, corporation, firm, enterprise, manufacturer, institution, charity, sole trader, association, or
parts or combination thereof.
[SOURCE: ISO/IEC/IEEE 9000:2015, 3.2.1, modified — Notes to entry have been removed; EXAMPLE has been
added.]
3.1.7
system
arrangement of parts or elements that together exhibit a stated behaviour or meaning that the individual
constituents do not
Note 1 to entry: A system is sometimes considered as a product or as the services it provides.
Note 2 to entry: In practice, the interpretation of its meaning is frequently clarified by the use of an associative noun, e.g.
aircraft system. Alternatively, the word “system” is substituted simply by a context-dependent synonym (e.g. aircraft),
though this potentially obscures a system principles perspective.
Note 3 to entry: A complete system includes all of the associated equipment, facilities, material, computer programs,
firmware, technical documentation, services, and personnel required for operations and support to the degree necessary
for self-sufficient use in its intended environment.
[SOURCE: ISO/IEC/IEEE 15288:2023, 3.46]
3.1.8
system element
discrete part of a system (3.1.7(3.1.7)) that can be implemented to fulfil specified requirements
© ISO/IEC/IEEE 2026 – All rights reserved
EXAMPLE Hardware, software, data, humans, processes [e.g. processes for providing service to users, procedures
[e.g., operator instructions], facilities, materials, and naturally occurring entities or any combination.
[SOURCE: ISO/IEC/IEEE 15288:2023, 3.47]
3.1.9
system of systems
SoS
set of systems (3.1.7(3.1.7)) and systemelements (3.1.8system elements (3.1.8)) that interact to provide a unique
capability (3.1.1()) that none of the constituent systems (3.1.2()) can accomplish on its own
Note 1 to entry: System elements can be necessary to facilitate interaction of the constituent systems in the SoS.
Note 2 to entry: A collection of systems is not always an SoS. The differences between a system and an SoS are not in the
structure of the parts, but rather in the managerial and operational independence of those parts. There is no distinct
boundary that separates systems from SoS, as the transition between the two is often gradual and context dependent.
[SOURCE: ISO/IEC/IEEE 21840:2026, —, 3.1.1311]
3.1.10
system of systems engineering
SoSE
process of planning, analysing, organizing, developing and integrating the capabilities (3.1.1()) of a mix of
existing and new systems (3.1.7(3.1.7),), including inter-system infrastructure, facilities, and overarching
processes into a system of systems (3.1.9(3.1.9)) capability that is greater than the sum of the capabilities of
the constituent systems (3.1.2())
Note 1 to entry: SoSE also includes testing, modification, maintenance and other post-integration activities.
[SOURCE: ISO/IEC/IEEE 21840:2026, —, 3.1.1412]
3.1.11
system -of -interest
SoI
system (3.1.7(3.1.7)) whose life cycle is under consideration
[SOURCE: ISO/IEC/IEEE15288:2023, 3.48]
3.1.12
systems engineering
transdisciplinary and integrative approach to enable the successful realization, use, and retirement of
engineered systems (3.1.7(3.1.7)) using systems principles and concepts and scientific, technological and
management (3.1.5(3.1.5)) methods
[SOURCE: INCOSE-TP-2020-002-06]
3.1.13
taxonomy
scheme that partitions a body of knowledge and defines the relationships among the parts
[SOURCE: ISO/IEC/IEEE 26531:2023, 3.1.30]
© ISO/IEC/IEEE 2026 – All rights reserved
3.2 SoS types
3.2.1
acknowledged SoS
acknowledged system of systems
SoS (3.1.10(3.1.10)) with recognized objectives, a designated manager, and resources
Note 1 to entry: Constituent systems (3.1.2()) retain their independent ownership, objectives, funding, and development
and sustainment approaches. Changes in the systems are based on cooperative agreements between the managers of the
SoS and the managers of the CS.
[SOURCE: ISO/IEC/IEEE 21840:2026,:—, 3.2.1]
3.2.2
collaborative SoS
collaborative system of systems
SoS (3.1.10(3.1.10)) in which constituent systems (CS) (3.1.2(3.1.2)) operationally interact more or less
voluntarily to fulfil agreed-upon central purposes
Note 1 to entry: Managers of CS or CS projects collaboratively decide how to provide or deny service, thereby providing
means of enforcing and maintaining consistency.
[SOURCE: ISO/IEC/IEEE 21840:2026, —, 3.2.2]
3.2.3
directed SoS
directed system of systems
SoS (3.1.10(3.1.10)) created and managed to fulfil specific purposes, with constituent systems (3.1.2()) that are
subordinated to the SoS
Note 1 to entry: Constituent systems maintain an ability to operate independently; however, their normal operational
mode is subordinated to the central managed purpose.
[SOURCE: ISO/IEC/IEEE 21840:2026, —, 3.2.3]
3.2.4
virtual SoS
virtual system of systems
SoS (3.1.10(3.1.10)) that lacks a central management (3.1.5(3.1.5)) authority and a centrally-agreed-upon
purpose
Note 1 to entry: Large-scale behaviour emerges—and can be desirable—but this type of SoS relies on relatively invisible
mechanisms to maintain it.
Note 2 to entry: Virtual SoS are typically self-organizing.
[SOURCE: ISO/IEC/IEEE 21840:2026 — 3.2.4]
4 Concepts and application
4.1 Overview
Taxonomies provide a means in many fields to classify and describe the relationships between the relevant
elements being studied. The elements of a taxonomy, individually called a taxon or collectively called taxa,
form a partitioning or means of classification within that body of knowledge. Partitioning based on essential
characteristics provides an abbreviated nomenclature to refer to a larger composite of characteristics,
facilitating discussion about the partitions (taxa) without having to refer to each of the characteristics.
© ISO/IEC/IEEE 2026 – All rights reserved
4.2 Importance of taxonomies to SoS
In systems engineering (SE), the relevant pieces of the system -of -interest (SoI) can be system elements or
components. In the context of SoS, the relevant pieces of the SoI are, by definition, systems themselves. These
are called constituent systems (CS) throughout this document. That is, an SoS consists of some number of CS,
plus any inter-system infrastructure, facilities and processes necessary to enable the CS to integrate or
interoperate. Relationships between CS affect the SoS. Using essential characteristics to partition the various
types of SoS provides an abbreviated nomenclature for thinking about SoS. While Clause 5 elaborates one
mature SoS taxonomy, Annex A provides a list of SoS less-mature taxonomies. Based on taxonomies, different
approaches to the engineering of systems of systems are possible, improving the efficiency and effectiveness
of SoSE.
NOTE 1 Taxonomies can have some overlap in their definition and do not need to be orthogonal to each other to be
useful. An SoS can be considered as belonging to several taxonomies as long as its characteristics meet the definitions of
the taxonomies.
NOTE 2 It is possible that inter-system infrastructure, facilities and processes do not meet the criteria for being
systems in their own right. From the perspective of the SoS, these can be system elements (or SoS elements).
4.3 Use of SoS taxonomies
There are many characteristics such as scale and scope, around which taxonomies can be derived. The SoS
taxonomy in Clause 5 organizes the relevant aspects or essential characteristics of SoS, providing specific
viewpoints that align with stakeholder concerns. This organization facilitates communications between the
various stakeholders that are involved with activities like governance, engineering, operation and
management of these SoS, and provides a reference for other related standards. The taxonomy in Clause 5
meets the following criteria.
— External references are publicly available.
— The taxa are stable with evidence of having been applied in multiple systems.
Annex A lists additional SoS taxonomies.
5 Taxonomies for systems of systems
5.1 General
SoS taxonomies organize the relevant aspects or essential characteristics of SoS, providing specific viewpoints
that align with stakeholder concerns. Taxonomies can have some overlap in their construction, but the lack of
orthogonality does not inhibit their application.
Since most of the taxonomies are not explicitly named, they are most often referenced in practice by the
author’s names or the names of the taxa. Consequently, the taxonomies are presented using the taxa names
themselves, using the author’s order.
5.2 Taxonomy: directed, acknow
...