SIST EN ISO 9241-20:2022
(Main)Ergonomics of human-system interaction - Part 20: An ergonomic approach to accessibility within the ISO 9241 series (ISO 9241-20:2021)
Ergonomics of human-system interaction - Part 20: An ergonomic approach to accessibility within the ISO 9241 series (ISO 9241-20:2021)
This document provides:
a) an introduction to the importance of accessibility to human-system interaction;
b) a discussion of the relationship of principles within the ISO 9241 series and accessibility;
c) descriptions of activities related to the processes in ISO 9241-210 that focus on accessibility;
d) references to standards relevant to the accessibility of interactive systems
Ergonomie der Mensch-System-Interaktion - Teil 20: Ein ergonomischer Ansatz für die Barrierefreiheit innerhalb der ISO 9241-Reihe (ISO 9241-20:2021)
Dieses Dokument enthält:
a) eine Einführung in die Bedeutung von Barrierefreiheit für die Mensch-System-Interaktion,
b) eine Diskussion des Zusammenhangs zwischen Grundsätzen der Normenreihe ISO 9241 und der Barrierefreiheit,
c) Beschreibungen von Tätigkeiten im Zusammenhang mit den Prozessen in ISO 9241-210, die sich auf die Barrierefreiheit beziehen,
d) Verweisungen auf Normen, die hinsichtlich der Barrierefreiheit von interaktiven Systemen relevant sind.
Ergonomie de l’interaction homme-système - Partie 20 : Approche ergonomique de l’accessibilité dans la série ISO 9241 (ISO 9241-20:2021)
Le présent document fournit:
a) une introduction à l’importance de l’accessibilité pour l’interaction homme-système;
b) une analyse de la relation entre les principes figurant dans la série ISO 9241 et l’accessibilité;
c) les descriptions des activités liées aux processus énoncés dans l’ISO 9241-210 qui se concentrent sur l’accessibilité;-
d) des références aux normes relatives à l’accessibilité des systèmes interactifs.
Ergonomija medsebojnega vpliva človek-sistem - 20. del: Ergonomski pristop k dostopnosti v skupini ISO 9241 (ISO 9241-20:2021)
Ta dokument zajema:
a) uvod v pomembnost dostopnosti medsebojnega vpliva človek-sistem;
b) razpravo o razmerju med načeli v skupini standardov ISO 9241 in dostopnostjo;
c) opise dejavnosti v povezavi s postopki iz standarda ISO 9241-210, ki se osredotočajo na dostopnost;
d) sklice na standarde, ki so pomembni za dostopnost interaktivnih sistemov.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 9241-20:2022
01-maj-2022
Nadomešča:
SIST EN ISO 9241-20:2009
Ergonomija medsebojnega vpliva človek-sistem - 20. del: Ergonomski pristop k
dostopnosti v skupini ISO 9241 (ISO 9241-20:2021)
Ergonomics of human-system interaction - Part 20: An ergonomic approach to
accessibility within the ISO 9241 series (ISO 9241-20:2021)
Ergonomie der Mensch-System-Interaktion - Teil 20: Ein ergonomischer Ansatz für die
Barrierefreiheit innerhalb der ISO 9241-Reihe (ISO 9241-20:2021)
Ergonomie de l’interaction homme-système - Partie 20 : Approche ergonomique de
l’accessibilité dans la série ISO 9241 (ISO 9241-20:2021)
Ta slovenski standard je istoveten z: EN ISO 9241-20:2021
ICS:
13.180 Ergonomija Ergonomics
35.180 Terminalska in druga IT Terminal and other
periferna oprema IT peripheral equipment
SIST EN ISO 9241-20:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 9241-20:2022
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SIST EN ISO 9241-20:2022
EN ISO 9241-20
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2021
EUROPÄISCHE NORM
ICS 13.180; 35.180 Supersedes EN ISO 9241-20:2009
English Version
Ergonomics of human-system interaction - Part 20: An
ergonomic approach to accessibility within the ISO 9241
series (ISO 9241-20:2021)
Ergonomie de l'interaction homme-système - Partie 20 Ergonomie der Mensch-System-Interaktion - Teil 20:
: Approche ergonomique de l'accessibilité dans la série Ein ergonomischer Ansatz für die Barrierefreiheit
ISO 9241 (ISO 9241-20:2021) innerhalb der ISO 9241-Reihe (ISO 9241-20:2021)
This European Standard was approved by CEN on 25 October 2021.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 9241-20:2021 E
worldwide for CEN national Members.
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SIST EN ISO 9241-20:2022
EN ISO 9241-20:2021 (E)
Contents Page
European foreword . 3
2
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SIST EN ISO 9241-20:2022
EN ISO 9241-20:2021 (E)
European foreword
This document (EN ISO 9241-20:2021) has been prepared by Technical Committee ISO/TC 159
"Ergonomics" in collaboration with Technical Committee CEN/TC 122 “Ergonomics” the secretariat of
which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by June 2022, and conflicting national standards shall be
withdrawn at the latest by June 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 9241-20:2009.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 9241-20:2021 has been approved by CEN as EN ISO 9241-20:2021 without any
modification.
3
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SIST EN ISO 9241-20:2022
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SIST EN ISO 9241-20:2022
INTERNATIONAL ISO
STANDARD 9241-20
Second edition
2021-11
Ergonomics of human-system
interaction —
Part 20:
An ergonomic approach to
accessibility within the ISO 9241
series
Ergonomie de l’interaction homme-système —
Partie 20: Approche ergonomique de l’accessibilité dans la série ISO
9241
Reference number
ISO 9241-20:2021(E)
© ISO 2021
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SIST EN ISO 9241-20:2022
ISO 9241-20:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
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
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© ISO 2021 – All rights reserved
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SIST EN ISO 9241-20:2022
ISO 9241-20:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Accessibility and ergonomics of human-system interaction . 2
5 Ergonomic principles in the ISO 9241 series supporting accessibility .2
5.1 General . 2
5.2 Principles from ISO 9241-171 . 2
5.2.1 Suitability for the widest range of use . 2
5.2.2 Equitable use. 3
5.2.3 Robustness . . . 3
5.3 Principles from ISO 9241-110 . 3
5.3.1 Suitability for the user's tasks . 3
5.3.2 Self-descriptiveness . 4
5.3.3 C onformity with user expectations . 4
5.3.4 Learnability . 5
5.3.5 Controllability . 5
5.3.6 Use error robustness . 5
5.3.7 Approachability . 6
5.4 Additional specialized principles in the ISO 9241 series . 6
5.4.1 Principles from ISO 9241-112 . 6
5.4.2 Principles from ISO 9241-400. 7
5.4.3 Principles from ISO 9241-500 . 7
5.5 Principles of human-centred design from ISO 9241-210 . 8
6 Accessibility-focused design activities within projects . 8
6.1 General . 8
6.2 Activities and their inputs . 8
6.3 User input to activities . 10
6.4 Understand and identify the users and the context of use. 11
6.4.1 Scoping . 11
6.4.2 The importance of users . 11
6.4.3 User groups . 11
6.4.4 Requirements specification .12
6.5 Produce solutions to meet the user requirements .12
6.5.1 High-level approach .12
6.5.2 Developing the solution .13
6.5.3 Detailed design decisions . 13
6.5.4 E valuation as design progresses . 13
6.5.5 Iteration .13
6 . 6 E v a lu at ion . 13
6.6.1 E valuation from the earliest stages . 13
6.6.2 Focus on evaluation from the user's perspective . 14
6.6.3 Iteration and feedback . 14
6.6.4 C onformity assessment . 14
Annex A (informative) Major sources of international-level accessibility guidelines .15
Bibliography .17
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SIST EN ISO 9241-20:2022
ISO 9241-20:2021(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 documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. 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.html.
This document was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee
SC 4, Ergonomics of human-system interaction, in collaboration with the European Committee for
Standardization (CEN) Technical Committee CEN/TC 122, Ergonomics, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 9241-20:2008), which has been technically
revised.
The main changes are as follows:
— The guidance in the previous edition has been replaced by references to many different standards
that now contain applicable guidance.
A list of all parts in the ISO 9241 series can be found on the ISO website.
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.
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SIST EN ISO 9241-20:2022
ISO 9241-20:2021(E)
Introduction
The ISO 9241 series provides ergonomic guidance that contributes to the accessibility of interactive
systems to meet the needs of users.
Two parts of ISO 9241 particularly address accessibility: ISO 9241-171 and ISO 9241-971. In addition, a
number of parts in the ISO 9241 series integrate guidance supporting accessibility.
Accessibility in the design of products, systems and services is important to ensure that they are usable
by the widest possible range of users. Designed solutions that support accessibility result from the
understanding and implementation of user requirements, including those user requirements specific to
accessibility.
Ergonomic principles and human-centred design activities contained in the ISO 9241 series provide a
basis for identifying user accessibility needs and deriving user requirements specific to accessibility.
This document identifies standards within the ISO 9241 series and in other related standards that
contain guidance related to accessibility.
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SIST EN ISO 9241-20:2022
INTERNATIONAL STANDARD ISO 9241-20:2021(E)
Ergonomics of human-system interaction —
Part 20:
An ergonomic approach to accessibility within the ISO
9241 series
1 Scope
This document provides:
a) an introduction to the importance of accessibility to human-system interaction;
b) a discussion of the relationship of principles within the ISO 9241 series and accessibility;
c) descriptions of activities related to the processes in ISO 9241-210 that focus on accessibility;
d) references to standards relevant to the accessibility of interactive systems.
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 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/
3.1
accessibility
extent to which products, systems, services, environments and facilities can be used by people from a
population with the widest range of user needs, characteristics and capabilities to achieve identified
goals in identified contexts of use
Note 1 to entry: Context of use includes direct use or use supported by assistive technologies.
[SOURCE: ISO 9241-112:2017, 3.15]
3.2
usability
extent to which a system, product or service can be used by specified users to achieve specified goals
with effectiveness, efficiency and satisfaction in a specified context of use
Note 1 to entry: The “specified” users, goals and context of use refer to the particular combination of users, goals
and context of use for which usability is being considered.
Note 2 to entry: The word “usability” is also used as a qualifier to refer to the design knowledge, competencies,
activities and design attributes that contribute to usability, such as usability expertise, usability professional,
usability engineering, usability method, usability evaluation, usability heuristic.
[SOURCE: ISO 9241-11:2018, 3.1.1]
1
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SIST EN ISO 9241-20:2022
ISO 9241-20:2021(E)
3.3
user
person who interacts with a system, product or service
Note 1 to entry: Users of a system, product or service include people who operate the system, people who make
use of the output of the system and people who support the system (including providing maintenance and
training).
[SOURCE: ISO 9241-11:2018, 3.1.7]
3.4
user accessibility need
user need related to features or attributes that are necessary for a system to be accessible
Note 1 to entry: User accessibility needs vary over time and across contexts of use.
Note 2 to entry: User accessibility needs are transformed into user requirements considering the context of use,
user priorities, trade-offs with other system requirements and constraints.
[SOURCE: ISO/IEC 29138-1:2018, 3.10]
4 Accessibility and ergonomics of human-system interaction
Accessibility in the design of products, systems and services is important to ensure that they are usable
by the widest possible range of users.
Design solutions that support accessibility result from understanding and application of specific user
requirements, including those user requirements specific to accessibility.
While the ISO 9241 series currently contains two standards specifically focused on accessibility
(ISO 9241-171 and ISO 9241-971), all parts of the ISO 9241 series provide ergonomic guidance that can
benefit accessible design solutions. Additionally, ISO 9241-220 identifies the concept of human-centred
quality, which includes accessibility as one of its four main components.
Planning for accessibility as an integral part of the human-centred design process (as described in
ISO 9241-210 and ISO 9241-220) involves the systematic identification of requirements for accessibility,
including accessibility measurements and verification criteria within the context of use. These provide
design targets that can form the basis for verification of the resulting design.
5 Ergonomic principles in the ISO 9241 series supporting accessibility
5.1 General
There are many principles contained within the ISO 9241 series that provide important support for
accessibility. Violating any of these principles will limit the accessibility of any resulting system,
product or service.
This clause identifies both principles and sources of guidance related to these principles that are found
in the ISO 9241 series.
NOTE Annex A contains further information about major sources of international-level accessibility
guidance.
5.2 Principles from ISO 9241-171
5.2.1 Suitability for the widest range of use
ISO 9241-171:2008, Clause 5, contains the principle of “suitability for the widest range of use”, which
it says “involves designing with the objective of producing solutions that will be useful, acceptable
2
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SIST EN ISO 9241-20:2022
ISO 9241-20:2021(E)
and available to the widest range of users within the intended user population, taking account of
their special abilities, variations in their capabilities, the diversity of their tasks, and their differing
environmental, economic and social circumstances.”
NOTE ISO/IEC Guide 71:2014, 6.2.1 transforms this principle into a goal it calls “suitability for the widest
range of users”. It explains that “A system is suitable for the widest range of users if it meets the needs of diverse
users in diverse contexts.”
ISO 9241-11:2018, 3.1.7, defines a user as a “person who interacts with a system, product or service”.
It recognizes that, “the objective of designing for accessibility is to enable products, systems, services,
environments and facilities to be used by people with the widest range of user needs, characteristics
and capabilities in diverse contexts of use. Accessibility is included as a component of human-centred
quality to emphasize its importance as part of human-centred design.”
While the accessibility guidance in ISO 9241-171 and ISO 9241-971 can support suitability for the widest
range of users, there are no parts of the ISO 9241 series that provide guidance on identifying the widest
range of users.
5.2.2 Equitable use
ISO 9241-171:2008, Clause 5, contains the principle of “equitable use”, which it describes thus: “Equitable
solutions provide the same means of use for all users: identical whenever possible; equivalent when not.
Achieving equitable use will ensure that solutions designed to increase accessibility do not result in
such things as loss of privacy, increased risks to personal safety or security, or the stigmatization of
individuals.”
NOTE ISO/IEC Guide 71:2014, 6.2.10 transforms this principle into a goal it calls “equitable use”. It explains
that “A system provides equitable use if it allows diverse users to accomplish tasks in an identical manner
whenever possible or in an equivalent manner when an identical manner is not possible.”
5.2.3 Robustness
ISO 9241-171:2008, Clause 5, contains the principle of “robustness”, which it describes thus: “Software
should be designed to be as robust as possible to allow it to work with current and future assistive
technologies. Although it is not feasible to make all software accessible without add-on assistive
technologies, these guidelines should help designers develop software that increases accessibility
without the use of assistive technologies, and, by providing the necessary interface information,
enables assistive software and devices to operate effectively and efficiently when used. The software
can promote integration of assistive technologies by providing information that can be read by assistive
technologies, and by communicating through standard application-to-application communication
protocols.”
NOTE ISO/IEC Guide 71:2014, 6.2.11 transforms this principle into a goal it calls “compatibility with other
systems”. It explains that “A system provides compatibility if it allows diverse users to use other systems as a
means to interact with it to accomplish the task.”
5.3 Principles from ISO 9241-110
5.3.1 Suitability for the user's tasks
ISO 9241-110:2020, 5.1 contains the principle of “suitability for the user's tasks”, which it describes
thus: “An interactive system is suitable for the user's tasks when it supports users in the completion
of their tasks, i.e. when the operating functions and the user-system interactions are based on the
task characteristics (rather than the technology chosen to perform the task).” It also notes that, “A
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SIST EN ISO 9241-20:2022
ISO 9241-20:2021(E)
prerequisite for suitability for the user’s tasks is that the tasks themselves have been based on user
needs.”
NOTE ISO/IEC Guide 71:2014, 6.2.8 replaces this principle with a goal that it calls “usability”. It explains
that “A system is usable if it supports diverse users in their diverse contexts to accomplish their tasks with
effectiveness, efficiency and satisfaction.” The ISO 9241 series recognizes usability as an outcome of use, rather
than as a goal. ISO 9241-11 provides definitions and concepts related to usability.
ISO 9241-110 provides general design recommendations related to suitability for the user's tasks,
including guidance on:
— identifying suitability of the interactive system for a given task;
— optimizing effort in task accomplishment;
— defaults supporting the task.
5.3.2 Self-descriptiveness
ISO 9241-110:2020, 5.2 contains the principle of “self-descriptiveness”, which it describes thus: “The
interactive system presents appropriate information, where needed by the user, to make its capabilities
and use immediately obvious to the user without the need for unnecessary user-system interactions.”
NOTE ISO/IEC Guide 71:2014, 6.2.5 and 6.2.6 replaces this principle with two goals:
— “perceivability”, which it describes thus: “A system is perceivable if diverse users in diverse contexts can
sense the information and functionalities it presents.”
— “understandability”, which it describes thus: “A system is understandable if its information and functionalities
are interpretable by diverse users.”
ISO 9241-110 provides general design recommendations related to self-descriptiveness, including
guidance on:
— presence and obviousness of information;
— clear indication of processing status.
ISO 9241-112 provides ergonomic guidance on the presentation of in
...
SLOVENSKI STANDARD
oSIST prEN ISO 9241-20:2021
01-julij-2021
Ergonomija medsebojnega vpliva človek-sistem - 20. del: Ergonomski pristop k
dostopnosti v skupini ISO 9241 (ISO/DIS 9241-20:2021)
Ergonomics of human-system interaction - Part 20: An ergonomic approach to
accessibility within the ISO 9241 series (ISO/DIS 9241-20:2021)
Ergonomie der Mensch-System-Interaktion - Teil 20: Ein ergonomischer Ansatz für die
Barrierefreiheit innerhalb der ISO 9241-Reihe (ISO/DIS 9241-20:2021)
Ergonomie de l’interaction homme-système - Partie 20 : Approche ergonomique de
l’accessibilité dans la série ISO 9241 (ISO/DIS 9241-20:2021)
Ta slovenski standard je istoveten z: prEN ISO 9241-20
ICS:
13.180 Ergonomija Ergonomics
35.180 Terminalska in druga IT Terminal and other
periferna oprema IT peripheral equipment
oSIST prEN ISO 9241-20:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN ISO 9241-20:2021
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oSIST prEN ISO 9241-20:2021
DRAFT INTERNATIONAL STANDARD
ISO/DIS 9241-20
ISO/TC 159/SC 4 Secretariat: BSI
Voting begins on: Voting terminates on:
2021-04-28 2021-07-21
Ergonomics of human-system interaction —
Part 20:
An ergonomic approach to accessibility within the ISO
9241 series
ICS: 35.180; 13.180
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT 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
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WHICH REFERENCE MAY BE MADE IN
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RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
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©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2021
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oSIST prEN ISO 9241-20:2021
ISO/DIS 9241-20:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
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 © ISO 2021 – All rights reserved
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oSIST prEN ISO 9241-20:2021
ISO/DIS 9241-20:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative References . 1
3 Terms and Definitions . 1
4 Accessibility and ergonomics of human-system interaction . 2
5 Ergonomic principles in the ISO 9241 series supporting accessibility .2
5.1 General . 2
5.2 Principles from ISO 9241-171 Guidance on software accessibility . 2
5.2.1 Suitability for the widest range of use . 2
5.2.2 Equitable use . 3
5.2.3 Robustness . 3
5.3 Principles from ISO 9241-110 Interaction principles . 3
5.3.1 Suitability for the user's tasks . 3
5.3.2 Self-descriptiveness . 4
5.3.3 Conformity with user expectations . 4
5.3.4 Learnability . 4
5.3.5 Controllability . 5
5.3.6 Use error robustness . 5
5.3.7 Approachability . 6
5.4 Additional more specialized principles in the ISO 9241 series . 6
5.4.1 Principles from ISO 9241-112 Principles for the presentation of information . 6
5.4.2 Principles from ISO 9241-400 Principles and requirements for physical
input devices . 6
5.4.3 Principles from ISO 9241-500 Ergonomic principles for the design and
evaluation of environments of interactive systems . 7
5.5 Principles of human-centred design from ISO 9241-210 Human-centred design
for interactive systems . 8
6 Accessibility focused design activities within projects . 8
6.1 General . 8
6.2 Activities and their inputs . 8
6.3 User input to activities .10
6.4 Understand and identify the users and the context of use .11
6.4.1 Scoping .11
6.4.2 The importance of users .11
6.4.3 User groups .11
6.4.4 Requirements specification .12
6.5 Produce solutions to meet the user requirements.12
6.5.1 High level approach .12
6.5.2 Developing the solution .13
6.5.3 Detailed design decisions .13
6.5.4 Evaluation as design progresses .13
6.5.5 Iteration .13
6.6 Evaluation .13
6.6.1 Evaluation from the earliest stages .13
6.6.2 Focus on evaluation from the user's perspective .14
6.6.3 Iteration and feedback .14
6.6.4 Conformity assessment .14
Annex A (informative) Major sources of international-level accessibility guidelines .15
Bibliography .18
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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 documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. 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 on 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 the following
URL: www .iso .org/ iso/ foreword .html.
This document was prepared by ISO/TC TC159 Ergonomics, Subcommittee SC 4, Ergonomics of human-
system interaction.
This second edition cancels and replaces the first edition (ISO 9241-20:2008), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— The guidance in the first version has been replaced by references to many different standards that
now contain applicable guidance.
A list of all parts in the ISO 9241 series can be found on the ISO website.
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Introduction
The ISO 9241 series provides ergonomic guidance that contributes to accessibility of interactive
systems to meet the needs of users.
Two parts of ISO 9241 particularly address accessibility: ISO 9241-171 and ISO 9241-971. In addition, a
number of additional parts in the ISO 9241 series integrate guidance supporting accessibility.
Accessibility in the design of products, systems, and services is important to ensure that they are usable
by the widest possible range of users. Designed solutions that support accessibility result from the
understanding and implementation of user requirements, including those user requirements specific to
accessibility.
Ergonomic principles and human-centred design activities contained in the ISO 9241 series provide a
basis for identifying user accessibility needs and deriving user requirements specific to accessibility.
This document identifies standards within the ISO 9241 series and in other related standards that
contain guidance related to accessibility.
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DRAFT INTERNATIONAL STANDARD ISO/DIS 9241-20:2021(E)
Ergonomics of human-system interaction —
Part 20:
An ergonomic approach to accessibility within the ISO
9241 series
1 Scope
This document provides
a) an introduction to the importance of accessibility to human-systems interaction
b) a discussion of the relationship of principles within the ISO 9241 series and accessibility
c) activities related to the processes in ISO 9241-210 that focus on accessibility;
d) references to standards relevant to the accessibility of interactive systems.
2 Normative References
There are no normative references.
3 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
3.1
accessibility
extent to which products, systems, services, environments and facilities can be used by people from a
population with the widest range of user needs, characteristics and capabilities to achieve identified
goals in identified contexts of use
Note 1 to entry: Context of use includes direct use or use supported by assistive technologies.
[SOURCE: ISO 9241-112:2017, 3.17]
3.2
usability
extent to which a system, product or service can be used by specified users to achieve specified goals
with effectiveness, efficiency and satisfaction in a specified context of use
Note 1 to entry: The “specified” users, goals and context of use refer to the particular combination of users, goals
and context of use for which usability is being considered.
Note 2 to entry: The word “usability” is also used as a qualifier to refer to the design knowledge, competencies,
activities and design attributes that contribute to usability, such as usability expertise, usability professional,
usability engineering, usability method, usability evaluation, usability heuristic.
[SOURCE: ISO 921-11:2018, 3.1.1]
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3.3
user
person who interacts with a system, product or service
Note 1 to entry: Users of a system, product or service include people who operate the system, people who make
use of the output of the system and people who support the system (including providing maintenance and
training).
[SOURCE: ISO 9241-11:2018, 3.1.7]
3.4
user accessibility need
user need related to features or attributes that are necessary for a system to be accessible
Note 1 to entry: User accessibility needs vary over time and across contexts of use.
Note 2 to entry: User accessibility needs are transformed into user requirements considering the context of use,
user priorities, trade-offs with other system requirements and constraints.
[SOURCE: ISO/IEC 29138-1:2018, 3.10]
4 Accessibility and ergonomics of human-system interaction
Accessibility in the design of products, systems, and services is important to ensure that they are usable
by the widest possible range of users.
Design solutions that support accessibility result from understanding and application of specific user
requirements, including those user requirements specific to accessibility.
While the ISO 9241 series currently contains two standards specifically focused on accessibility
(ISO 9241-171 and ISO 9241-971), all parts of the ISO 9241 series provide ergonomic guidance that can
benefit accessible design solutions. Additionally ISO 9241-220 identifies the concept of human-centred
quality which includes accessibility as one of its four main components.
Planning for accessibility as an integral part of the human-centred design process (as described in
ISO 9241-210 and ISO 9241-220) involves the systematic identification of requirements for accessibility,
including accessibility measurements and verification criteria within the context of use. These provide
design targets that can form the basis for verification of the resulting design.
5 Ergonomic principles in the ISO 9241 series supporting accessibility
5.1 General
There are many principles contained within the ISO 9241 series that provide important support for
accessibility. Violating any of these principles will limit the accessibility of any resulting system,
product, or service.
This clause identifies both principles and sources of guidance related to these principles that are found
in the ISO 9241 series.
5.2 Principles from ISO 9241-171 Guidance on software accessibility
5.2.1 Suitability for the widest range of use
ISO 9241-171:2007 contains the principle of “suitability for the widest range of use” which it describes
as: “Suitability for the widest range of use involves designing with the objective of producing solutions
that will be useful, acceptable and available to the widest range of users within the intended user
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population, taking account of their special abilities, variations in their capabilities, the diversity of their
tasks, and their differing environmental, economic and social circumstances.”
NOTE ISO/IEC Guide 71:2014 transformed this principle into a goal it names “Suitability for the widest range
of users” which it describes as: “A system is suitable for the widest range of users if it meets the needs of diverse
users in diverse contexts.”
ISO 9241-11:2018 defines users in terms of their interaction with a system, product, or service. It
recognizes that, “The objective of designing for accessibility is to enable products, systems, services,
environments and facilities to be used by people with the widest range of user needs, characteristics
and capabilities in diverse contexts of use. Accessibility is included as a component of human-centred
quality to emphasize its importance as part of human-centred design.”
While the accessibility guidance in ISO 9241-171 and ISO 9241-971 can support suitability for the widest
range of users, there are no parts in the ISO 9241 series that provide guidance on identifying the widest
range of users.
5.2.2 Equitable use
ISO 9241-171:2007 contains the principle of “equitable use” which it describes as: “Equitable solutions
provide the same means of use for all users: identical whenever possible; equivalent when not. Achieving
equitable use will ensure that solutions designed to increase accessibility do not result in such things
as loss of privacy, increased risks to personal safety or security, or the stigmatization of individuals.”
NOTE ISO/IEC Guide 71:2014 transformed this principle into a goal it names “Equitable use” which it
describes as: “A system provides equitable use if it allows diverse users to accomplish tasks in an identical
manner whenever possible or in an equivalent manner when an identical manner is not possible.”
5.2.3 Robustness
ISO 9241-171:2007 contains the principle of “robustness” which it describes as: “Software should be
designed to be as robust as possible to allow it to work with current and future assistive technologies.
Although it is not feasible to make all software accessible without add-on assistive technologies, these
guidelines should help designers develop software that increases accessibility without the use of
assistive technologies, and, by providing the necessary interface information, enables assistive software
and devices to operate effectively and efficiently when used. The software can promote integration
of assistive technologies by providing information that can be read by assistive technologies, and by
communicating through standard application-to-application communication protocols.”
NOTE ISO/IEC Guide 71:2014 transformed this principle into a goal it names “compatibility with other
systems” which it describes as: “A system provides compatibility if it allows diverse users to use other systems
as a means to interact with it to accomplish the task.”
5.3 Principles from ISO 9241-110 Interaction principles
5.3.1 Suitability for the user's tasks
ISO 9241-110:2019 contains the principle of “suitability for the user's tasks” which it describes as: “An
interactive system is suitable for the user's tasks when it supports users in the completion of their tasks,
i.e. when the operating functions and the user-system interactions are based on the task characteristics
(rather than the technology chosen to perform the task).” It also notes that, “A prerequisite for suitability
for the user’s tasks is that the tasks themselves have been based on user needs.”
NOTE ISO/IEC Guide 71:2014 replaced this principle with a goal that it names “usability” which it describes
as: “A system is usable if it supports diverse users in their diverse contexts to accomplish their tasks with
effectiveness, efficiency and satisfaction.” ISO 9241 recognizes usability as an outcome of use, rather than as a
goal. ISO 9241-11:2018 provides definitions and concepts related to usability.
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ISO 9241-110:2019 provides general design recommendations related to suitability for the user's tasks
including guidance on:
— identifying suitability of the interactive system for a given task,
— optimizing effort in task accomplishment,
— defaults supporting the task.
5.3.2 Self-descriptiveness
ISO 9241-110:2019 contains the principle of “self-descriptiveness” which it describes as: “The interactive
system presents appropriate information, where needed by the user, to make its capabilities and use
immediately obvious to the user without the need for unnecessary user-system interactions.”
NOTE ISO/IEC Guide 71:2014 replaced this principle with two goals:
— “perceivability” which it describes as: “A system is perceivable if diverse users in diverse contexts can sense
the information and functionalities it presents.”
— “understandability” which it describes as: “A system is understandable if its information and functionalities
are interpretable by diverse users.”
ISO 9241-110:2019 provides general design recommendations related to self-descriptiveness, including
guidance on:
— presence and obviousness of information,
— clear indication of processing status.
ISO 9241-112:2017 provides ergonomic guidance on the presentation of information. (See also
Clause 5.4)
5.3.3 Conformity with user expectations
ISO 9241-110:2019 contains the principle of “conformity with user expectations” which it describes as:
“The interactive system’s behaviour is predictable based on the context of use and commonly accepted
conventions in this context.”
NOTE ISO/IEC Guide 71:2014 transformed this principle into a goal it names “conformity with user
expectations” which it describes as: “A system conforms to user expectations if it is predictable based on the
user’s past experience, the context of use, laws and standards, and/or commonly accepted conventions.”
ISO 9241-110:2019 provides general design recommendations related to conformity with user
expectations, including guidance on:
— appropriate system behaviour and responses,
— consistency (internal and external),
— changes in the context of use.
5.3.4 Learnability
ISO 9241-110:2019 contains the principle of “learnability” which it describes as: “The interactive system
supports discovery of its capabilities and how to use them, allows exploration of the interactive system,
minimizes the need for learning and provides support when learning is needed.”
NOTE ISO/IEC Guide 71 combined the ISO 9241-110 principles of “suitability for the task” and “learnability”
within its goal of “usability”. (See 5.3.1 for a discussion of this ISO/IEC Guide 71 goal).
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ISO 9241-110:2019 provides general design recommendations related to learnability including
guidance on:
— discovery (of information and controls that users are looking for),
— exploration (of information and controls that users have discovered),
— retention (of information about the system).
5.3.5 Controllability
ISO 9241-110:2006 contained a principle of “suitability for individualization” which it described as:
“A dialogue is capable of individualization when users can modify interaction and presentation of
information to suit their individual capabilities and needs.”
ISO 9241-110:2019 recognizes that individualization is a major component of controllability and thus
has combined individualization within its principle of “controllability”.
ISO 9241-110:2019 combines suitability for individualization and controllability into the principle of
“controllability” which it describes as: “The interactive system allows the user to maintain control of
the user interface and the interactions, including the speed and sequence and individualization of the
user-system interaction.”
NOTE ISO/IEC Guide 71:2014 transformed this principle into a goal it names “Controllability” which it
describes as: “A system is controllable if the user is able to initiate and complete the interaction(s) required to
accomplish the task.” It also retained a goal based on “suitability for individualization that it names “Support
for individualization” which it describes as: A system supports individualization if its components, functions or
operations can be tailored to meet the needs of individual users.”
ISO 9241-110:2019 provides general design recommendations related to controllability including
guidance on:
— interruption by the user,
— flexibility,
— individualization.
ISO 9241-920:2009 provides ergonomic guidance on the design of tactile/haptic controls.
ISO 9241-129:2010 provides ergonomic guidance on software individualization.
5.3.6 Use error robustness
ISO 9241-110:2019 has gone beyond error tolerance, which was a principle in ISO 9241-110:2006, and
renamed it as the principle of “Use error robustness” which it describes as: “The interactive system
assists the user in avoiding errors and in case of identifiable errors treats them tolerantly and assists
the user when recovering from errors.”
NOTE ISO/IEC
...
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