EN ISO 9241-20:2009

SLOVENSKI STANDARD
01-april-2009
(UJRQRPLMDPHGVHERMQHJDYSOLYDþORYHNVLVWHPGHO6PHUQLFH]DPRåQRVWL
XSUDYOMDQMDRSUHPHLQSURJUDPVNLKIXQNFLMLQIRUPDFLMVNHLQNRPXQLNDFLMVNH
WHKQRORJLMH,62
Ergonomics of human-system interaction - Part 20: Accessibility guidelines for
information/communication technology (ICT) equipment and services (ISO 9241-
20:2008)
Ergonomie der Mensch-System-Interaktion - Teil 20: Leitlinien für die Zugänglichkleit
von Informations- und Kommunikationstechnik und Dienstleistungen (ISO 9241-
20:2008)
Ergonomie de l'interaction homme-système - Partie 20: Lignes directrices sur
l'accessibilité de l'équipement et des services des technologies de l'information et de la
communication (TIC) (ISO 9241-20:2008)
Ta slovenski standard je istoveten z: EN ISO 9241-20:2009
ICS:
13.180 Ergonomija Ergonomics
35.180 Terminalska in druga IT Terminal and other
periferna oprema IT peripheral equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 9241-20
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2009
ICS 13.180; 35.180
English Version
Ergonomics of human-system interaction - Part 20: Accessibility
guidelines for information/communication technology (ICT)
equipment and services (ISO 9241-20:2008)
Ergonomie de l'interaction homme-système - Partie 20: Ergonomie der Mensch-System-Interaktion - Teil 20:
Lignes directrices sur l'accessibilité de l'équipement et des Leitlinien für die Zugänglichkeit der Geräte und Dienste in
services des technologies de l'information et de la der Informations- und Kommunikationstechnologie (ISO
communication (TIC) (ISO 9241-20:2008) 9241-20:2008)
This European Standard was approved by CEN on 29 December 2008.
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 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 Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2009 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 9241-20:2009: E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
The text of ISO 9241-20:2008 has been prepared by Technical Committee ISO/TC 159 “Ergonomics” of the
International Organization for Standardization (ISO) and has been taken over as EN ISO 9241-20:2009 by
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 July 2009, and conflicting national standards shall be withdrawn at the
latest by July 2009.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
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, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 9241-20:2008 has been approved by CEN as a EN ISO 9241-20:2009 without any
modification.
INTERNATIONAL ISO
STANDARD 9241-20
First edition
2008-03-01
Ergonomics of human-system
interaction —
Part 20:
Accessibility guidelines for
information/communication technology
(ICT) equipment and services
Ergonomie de l'interaction homme-système —
Partie 20: Lignes directrices sur l'accessibilité de l'équipement et des
services des technologies de l'information et de la communication (TIC)

Reference number
ISO 9241-20:2008(E)
©
ISO 2008
ISO 9241-20:2008(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2008
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2008 – All rights reserved

ISO 9241-20:2008(E)
Contents Page
Foreword. iv
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Application . 3
4.1 Principles. 3
4.2 Application framework . 4
4.3 Implementing the recommendations. 4
4.4 Conformance. 5
5 Accessibility . 7
5.1 General. 7
5.2 Context(s) of use and accessibility. 7
5.3 Process . 8
6 Recommendations related to managing development. 8
6.1 Information accessibility policy . 8
6.2 Development accountability . 8
7 Recommendations related to user characteristics . 8
7.1 General. 8
7.2 Vision . 11
7.3 Hearing. 12
7.4 Speech . 14
7.5 Physical capabilities. 14
7.6 Cognitive capabilities. 16
8 Recommendations related to task characteristics. 17
8.1 Performing tasks based on context of use . 17
8.2 Providing alternative ways of performing tasks. 18
8.3 Performing maintenance and other non-task related operations. 18
9 Recommendations related to equipment and service characteristics. 18
9.1 General. 18
9.2 Other standards for ICT equipment and services . 20
9.3 Assistive technologies. 20
9.4 Selection and operation of ICT equipment and services. 21
9.5 Preparation and completion of operation . 21
10 Recommendations related to environmental characteristics . 22
10.1 Operating in a range of environments. 22
10.2 Designing environments. 22
10.3 Impacting the environment. 23
Annex A (informative) Overview of the ISO 9241 series. 24
Annex B (informative) Sample checklist for assessing applicability and conformance of ICT
equipment and services. 28
Annex C (informative) User needs. 33
Bibliography . 42

ISO 9241-20:2008(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has
been established has the right to be represented on that committee. International organizations, governmental
and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 9241-20 was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 4,
Ergonomics of human-system interaction.
ISO 9241 consists of the following parts, under the general title Ergonomic requirements for office work with
visual display terminals (VDTs):
⎯ Part 1: General introduction
⎯ Part 2: Guidance on task requirements
⎯ Part 3: Visual display requirements
⎯ Part 4: Keyboard requirements
⎯ Part 5: Workstation layout and postural requirements
⎯ Part 6: Guidance on the work environment
⎯ Part 7: Requirements for display with reflections
⎯ Part 8: Requirements for displayed colours
⎯ Part 9: Requirements for non-keyboard input devices
⎯ Part 11: Guidance on usability
⎯ Part 12: Presentation of information
⎯ Part 13: User guidance
⎯ Part 14: Menu dialogues
⎯ Part 15: Command dialogues
⎯ Part 16: Direct manipulation dialogues
iv © ISO 2008 – All rights reserved

ISO 9241-20:2008(E)
⎯ Part 17: Form filling dialogues
Guidance on software individualization is to form the subject of a future part 129.
ISO 9241 also consists of the following parts, under the general title Ergonomics of human-system interaction:
⎯ Part 20: Accessibility guidelines for information/communication technology (ICT) equipment and services
⎯ Part 110: Dialogue principles
⎯ Part 151: Guidance on World Wide Web user interfaces
⎯ Part 171: Guidance on software accessibility
⎯ Part 300: Introduction to electronic visual display requirements
⎯ Part 302: Terminology for electronic visual displays
⎯ Part 303: Requirements for electronic visual displays
⎯ Part 304: User performance test methods
⎯ Part 305: Optical laboratory test methods for electronic visual displays
⎯ Part 306: Field assessment methods for electronic visual displays
⎯ Part 307: Analysis and compliance test methods for electronic visual displays
⎯ Part 308: Surface-conduction electron-emitter displays (SED) [Technical Report]
⎯ Part 400: Principles and requirements for physical input devices
⎯ Part 410: Design criteria for physical input devices
⎯ Part 920: Guidance on tactile and haptic interactions
Framework for tactile and haptic interaction is to form the subject of a future part 910.
ISO 9241-20:2008(E)
Introduction
The number of people using information/communication technologies (ICT) equipment and services, which
combine hardware, software and network technologies, is increasing, as is the variety of ICT equipment and
services. Our everyday lives are filled by such equipment and services.
This part of ISO 9241 is intended to help developers enable ICT equipment and services (and forthcoming
novel or innovative equipment and services) so that they can be used by the widest range of people,
regardless of their capabilities or disabilities, limitations or culture.
This part of ISO 9241 is based on the current understanding of the characteristics of individuals who have
particular physical, sensory and/or cognitive impairments. However, accessibility is an issue that affects many
people. The users of interactive systems are consumers or professionals with roles such as home occupiers,
school pupils, engineers, clerks, salespersons and web designers. The individuals in such target groups vary
significantly as regards physical, sensory and cognitive abilities and each target group will include people with
different abilities. Thus people with disabilities do not form a specific group that can be separated out and then
disregarded. The differences in capabilities may arise from a variety of factors that serve to limit the capability
to engage in the activities of daily living, and are a “universal human experience”. Therefore, accessibility
addresses a widely defined group of users including
⎯ people with physical, sensory and cognitive impairments present at birth or acquired during life,
⎯ elderly people (a growing percentage of the population), who can benefit from new products and services
but who experience reduced physical, sensory and cognitive capacities,
⎯ people with temporary disabilities, such as a person with a broken arm or someone without his or her
reading glasses, and
⎯ people who experience difficulties in particular situations, such as a person who works in a noisy
environment or has both hands occupied by other activities.
This part of ISO 9241 is prepared as guidance to secure and improve accessibility to ICT equipment, software
and services when they are used by people within the widest range of capabilities. It presents:
a) a framework based on the ergonomic concept of context of use, and
b) principles for the accessibility of ICT equipment and services.
Their presentation is intended to assist the users of this part of ISO 9241 in the consideration of accessibility
issues. It also describes major product attributes with design examples, provides information for the planning,
design and development of ICT equipment and services and acquisition and evaluation of ICT equipment and
services. It recognizes the importance of following general ergonomic guidance as well as the more
accessibility-specific guidance found in this and other accessibility-specific standards in achieving full use of
ICT equipment, software and services.
While many of the requirements and recommendations in this part of ISO 9241 also apply outside the domain
of accessibility, they are especially important to this domain. The checklist of Annex B has also been included
to help users examine the accessibility features of ICT equipment and services.

vi © ISO 2008 – All rights reserved

INTERNATIONAL STANDARD ISO 9241-20:2008(E)

Ergonomics of human-system interaction —
Part 20:
Accessibility guidelines for information/communication
technology (ICT) equipment and services
1 Scope
This part of ISO 9241 is intended for use by those responsible for planning, designing, developing, acquiring,
and evaluating information/communication technology (ICT) equipment and services. It provides guidelines for
improving the accessibility of ICT equipment and services such that they will have wider accessibility for use
at work, in the home, and in mobile and public environments. It covers issues associated with the design of
equipment and services for people with a wide range of sensory, physical and cognitive abilities, including
those who are temporarily disabled, and the elderly.
A detailed design for particular equipment or a service can be developed based on its recommendations. If a
specific detailed standard exists concerning the accessibility of equipment or services, then it can be used in
conjunction with that more specific standard. Where such standards are not available, this part of ISO 9241
can then form the basis for the design of the accessibility features of ICT equipment and services.
It also provides general guidelines for acquiring and evaluating ICT equipment and services, including both
hardware and software aspects of information processing equipment, electronic communication facilities,
office machines, and other similar technologies and services, used at work, in the home, and in mobile and
public environments.
In addition, it gives important information about context of use. Accessibility is increased by expanding the
range of contexts where equipment and services can be used. Context of use can result from the various
components of the equipment or service, including user, task and equipment (hardware, software and
materials) characteristics, as well as those of physical and social environments. Context of use can be
considered when planning, designing, developing, acquiring and evaluating ICT equipment and services.
NOTE This part of ISO 9241 is a high-level standard applicable to all ICT equipment and services, therefore, detailed
descriptions specific to equipment or services have been avoided. It can be referred to for the prevention of barriers to
trade or the movement of people in respect of each national, regional and international standardization activity in this area.
More specific recommendations on software accessibility are contained in ISO 9241-171.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 9241-5, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 5:
Workstation layout and postural requirements
ISO 9241-11:1998, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 11:
Guidance on usability
ISO 9241-12, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 12:
Presentation of information
ISO 9241-20:2008(E)
ISO 9241-13, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 13: User
guidance
ISO 9241-14, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 14: Menu
dialogues
ISO 9241-15, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 15:
Command dialogues
ISO 9241-16, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 16: Direct
manipulation dialogues
ISO 9241-17, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 17: Form
filling dialogues
ISO 9241-110:2006, Ergonomics of human-system interaction — Part 110: Dialogue principles
ISO 9241-151, Ergonomics of human-system interaction — Part 151: Guidance on World Wide Web user
1)
interfaces
1)
ISO 9241-171, Ergonomics of human-system interaction — Part 171: Guidance on software accessibility
ISO 9241-300, Ergonomics of human-system interaction — Part 300: Introduction to electronic visual display
1)
requirements
ISO 9241-302, Ergonomics of human-system interaction — Part 302: Terminology for electronic visual
1)
displays
ISO 9241-410, Ergonomics of human-system interaction — Part 410: Design criteria for physical input devices
ISO 13407:1999, Human-centred design processes for interactive systems
ISO 14915 (all parts), Software ergonomics for multimedia user interfaces
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
accessibility
〈interactive systems〉 usability of a product, service, environment or facility by people within the widest range
of capabilities
NOTE 1 The concept of accessibility addresses the full range of user capabilities and is not limited to users who are
formally recognized as having disability.
NOTE 2 The usability-oriented concept of accessibility aims to achieve levels of effectiveness, efficiency and
satisfaction that are as high as possible considering the specified context of use, while paying attention to the full range of
capabilities within the user population.
3.2
assistive technology
hardware or software, added to or incorporated within a system, which increases accessibility for an individual

1) To be published.
2 © ISO 2008 – All rights reserved

ISO 9241-20:2008(E)
3.3
context of use
users, tasks, equipment (hardware, software and materials), and the physical and social environments in
which a product is used
[ISO 9241-11:1998, definition 3.5]
3.4
information/communication technology
ICT
technology for gathering, storing, retrieving, processing, analysing and transmitting information
3.5
interactive system
combination of hardware and software components that receive input from, and communicate output to, a
human user in order to support his or her performance of a task
[ISO 13407:1999, definition 2.1]
NOTE The term “system” is often used rather than “interactive system”.
3.6
screen reader
assistive technology in combination with information available via the operating system that allows users to
navigate through windows, determine the state of controls, and read text through Braille or text-to-speech
conversion
3.7
usability
extent to which a product can be used by specified users to achieve specified goals with effectiveness,
efficiency and satisfaction in a specified context of use
[ISO 9241-11:1998, definition 3.1]
3.8
user
〈ICT〉 individual interacting with the ICT equipment or service
NOTE Adapted from ISO 9241-11:1998, definition 3.7 and ISO 9241-110:2006, definition 3.8.
4 Application
4.1 Principles
Design for accessibility should adhere to the following principles.
a) Suitability for the widest range of use
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 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.
b) Equitable use
Achieving equitable use will ensure that solutions designed to increase accessibility do not result in loss
of privacy, increased risks to personal safety or security, or the stigmatization of individuals, and that
solutions provide the same means of use for all users that are identical whenever possible; equivalent
when not.
ISO 9241-20:2008(E)
c) Robustness
Robustness involves supporting a wide range of options both in terms of the features provided by ICT
equipment or services and in terms of the ability to connect additional ICT equipment, software, and/or
services.
NOTE 1 Although it is not feasible to make all ICT operable without add-on assistive technologies, the application of
this part of ISO 9241 can help designers develop equipment and services that increases accessibility without the use of
assistive technologies. Additionally, by providing the necessary interface information, its application will enable assistive
software and devices to operate effectively and efficiently when used.
NOTE 2 ICT can promote integration of assistive technologies by providing information that can be read by those
technologies, and by communicating through standard application-to-application communication protocols. For example,
systems that provide built-in screen magnification can enable many more users to read the text and see the images that
are presented. However, if the necessary integration information is available, users can also attach the screen
magnification program of their choice to suit their particular needs.
4.2 Application framework
Accessibility results when ICT equipment and services can be used by all members of a population in which
individuals differ in their capabilities. Design solutions that support accessibility are not design for average
members of a population but for the widest possible range of users, including those with various disabilities.
The goal of these design solutions is to create ICT products and services that can be used by populations
including the widest possible range of individual differences. It is recognized (see ISO 9241-11) that the
usability of particular ICT equipment and services will vary between users within a population and depending
on the context of use. Accessibility, therefore, is not about achieving an equal level of usability for all
individuals, but rather about achieving at least some usability by all individuals. The guidance given by this
part of ISO 9241 can help achieve accessibility (in general) for diverse populations and help improve the
levels of accessibility for many individuals, when combined with an understanding of their context of use.
Design solutions that support accessibility result from understanding and application of specific user
requirements, including those user requirements specific to accessibility. These design solutions can benefit
from the guidance found in a range of International Standards, including this and other parts of ISO 9241.
Its recommendations are related to information accessibility policy and to user, task, equipment and service,
and environmental characteristics. It can be used to provide high level accessibility guidance together with
other International Standards, including the more detailed accessibility standard ISO 9241-171. Other
ergonomics standards, which may or may not have their own accessibility-related guidance (e.g.
ISO 9241-151 and ISO 14915), are also important in ensuring aspects of usability, which is the goal of
accessibility when applied to populations of users with differing capabilities.
Figure 1 shows how this part of ISO 9241 can be applied to improve the accessibility of ICT equipment and
services, used together with other parts of ISO 9241 and ISO 14915 to identify user requirements for the
accessibility of a product or service, and considering the context of use of the product or service. This context
of use includes user, task, equipment, service and environmental characteristics.
The resulting set of user requirements for accessibility can be used to form the basis for a design solution of
the product or service, which can then be evaluated against the identified user requirements for accessibility.
4.3 Implementing the recommendations
Individual recommendations of Clauses 6 to 10 should be evaluated for their applicability, taking account of
context of use.
A recommendation should not be implemented if there is evidence that to do so would cause deviation from
the design objectives.
NOTE A design objective is non-discriminatory if it does not exclude users because of diversity of capabilities.
4 © ISO 2008 – All rights reserved

ISO 9241-20:2008(E)
4.4 Conformance
If ICT equipment or services are claimed to have met the provisions of this part of ISO 9241, then the
procedures used to establish user requirements and to evaluate the equipment or service shall be specified.
The level of detail of the specification is a matter of negotiation between the involved parties. (Annex B
provides assistance in documenting conformance.)
ISO 9241-20:2008(E)
Figure 1 — Application of ISO 9241-20
6 © ISO 2008 – All rights reserved

ISO 9241-20:2008(E)
5 Accessibility
5.1 General
ICT equipment and services are generally designed for a limited range of contexts of use. Accessibility is only
achieved when the ICT equipment or service is designed to take sufficient account of the goals, abilities and
limitations of users and to support successful interaction. Factors that can limit accessibility arise from one or
more components of the context of use (i.e. user, task, equipment and/or environment) as well as interactions
between them. ICT equipment and services developed for a limited range of contexts of use risk having more
accessibility problems than systems developed for a wider range of context of use.
NOTE ICT equipment and services can be composed of many hardware and software components, including
assistive technologies.
Accessibility exists at various levels of equipment and services, within an individual user’s specific
environment, and can be different for different users. Accessibility can be improved by addressing users, tasks,
equipment and services and environment or the fit between these different elements in the context of use.
However, the improvement of individual elements cannot guarantee accessibility or even the improvement of
accessibility. What is needed is a holistic approach that seeks to optimize all of the elements. This can involve
training users, structuring tasks to suit the users, improving the environment and improving the design of
equipment and services.
5.2 Context(s) of use and accessibility
It is important to identify the context or contexts of use, involving users, tasks, social, and physical and
technical environments, which applies to the ICT equipment or service being developed or evaluated.
Guidance on the identification of the context of use is provided in ISO 9241-11, which shall be consulted when
applying this part of ISO 9241.
National accessibility legislation in many countries provides guidance and requirements that are not
addressed in this part of ISO 9241 but which should be considered within the context use.
In specifying the user groups, particular attention should be paid to identifying the range of user characteristics
that can be found within the user population, since the aim is to meet the needs of the widest possible range
of users. The accessibility of the equipment or service increases to the extent of the variation in the user
characteristics that is supported where users are able to achieve task goals.
The following approaches should be considered, in order to take account of the variation in user
characteristics.
a) ICT equipment and services are designed for use by the user population without need for any
modification or the connection of assistive technologies. This approach is important for ICT equipment
and services designed for use by the general public and/or on a “walk up and use” basis.
b) ICT equipment and services are designed to be configurable to meet individual user needs. This allows
users with different capabilities and preferences to select the ways in which they interact with the
equipment or service to optimize their effectiveness, efficiency and satisfaction.
c) Where approaches a) and b) above are not possible or are not appropriate, a range of ICT equipment or
services is provided which covers the needs of the whole user population. Each item in the range is
designed to meet the needs of subgroups of the user population and can be acquired on an individual
basis. This is particularly applicable in non-public situations where people are able to make a personal
choice.
d) While approaches a), b) and c) above can meet the needs of most people, it is possible that some people
will still have to use assistive technologies to support their interaction with ICT equipment and services.
The ability to connect assistive technologies, while not an accessibility approach on its own, provides the
basis for these users to create their own accessibility approaches.
ISO 9241-20:2008(E)
5.3 Process
The following activities should be performed to ensure accessibility:
⎯ understand and specify context of use, paying particular attention to the variation of user characteristics
and the impact of task, equipment and environmental characteristics that affect accessibility;
⎯ identify and specify the users' needs for accessibility;
⎯ produce design solutions paying particular attention to accessibility considerations;
⎯ evaluate accessibility design solutions of ICT equipment and services with users whose characteristics
reflect the targeted user groups.
For details, ISO 13407 shall be consulted.
NOTE 1 ISO/TR 16982 also provides guidance on usability methods that support human-centred design
NOTE 2 Evaluation of accessibility design solutions includes obtaining user test results and other available forms of
user feedback.
NOTE 3 In developments involving multiple parties, the means of achieving accessibility is a matter of negotiation and
agreement.
6 Recommendations related to managing development
6.1 Information accessibility policy
General managers and development managers should have an information accessibility policy.
EXAMPLE A company establishes a general information accessibility policy that includes a statement of accessibility
goals, a person responsible for ensuring that the company meets these goals, and the identification of particular
accessibility standards that it expects to meet.
6.2 Development accountability
General managers and development managers should ensure that the information accessibility policy is
followed in the planning, design, development and evaluation of ICT equipment and services.
The best outcome is usually achieved and at lower cost when information accessibility is addressed very early
in the design process.
7 Recommendations related to user characteristics
7.1 General
7.1.1 Supporting a range of user characteristics
The range of user characteristics supported by the ICT equipment and services should be sufficient to allow
the widest possible range of users to perform the tasks intended in the design.
Specific users may present combinations of disabilities that require specific solutions. A simple combination of
the solutions for each individual disability is not adequate. For instance, users who are deaf-blind often do not
benefit from auditory output of text like users who are blind nor from text output of audio like users who are
deaf.
EXAMPLE A system avoids imposing excessive loads on a user's permanent or temporary memory and learning
abilities and limitations.
8 © ISO 2008 – All rights reserved

ISO 9241-20:2008(E)
7.1.2 Supporting multiple interaction mechanisms
ICT equipment and services should support as many alternative means of interaction as possible in order to
support the accessibility needs of different groups of users.
When the operation of a particular mental or physical function is difficult for some group of users, an
alternative mental or physical function can be used to provide these users with access to the operation
performed by that function.
EXAMPLE 1 Voice recognition is provided as an alternative for people with difficulties typing/spelling.
EXAMPLE 2 An assistive technology uses keyboard equivalent input (such as the use of a keyboard or Braille input
device instead of a touch screen) for equipment or a service to meet the needs of people within the widest range of
capabilities.
EXAMPLE 3 For a graphical interface, users without vision are provided text equivalents for graphic objects through a
screen reader.
7.1.3 Supporting simultaneous use of alternate interaction mechanisms
ICT equipment and services should support simultaneous use of alternative means of interaction to meet the
accessibility needs of users in different or changing contexts.
This involves the use of multiple interaction channels (see also 7.3.10).
EXAMPLE A screen reader is able to access text output from the operating system and sends it in speech or Braille
in addition to a display screen Individualization
7.1.4 Supporting individualization
ICT equipment and services should support individualization by users (7.3.8 and 7.6.7 provide guidance on
two specific uses of individualization).
EXAMPLE 1 The user is allowed to select which input and output devices to use for a given task.
EXAMPLE 2 The physical repositioning of individual devices can be easily accomplished by the user.
EXAMPLE 3 The user is allowed to rearrange the layout of components on a display by dragging and dropping.
7.1.5 Changing configurations
A method that does not require users to reconfigure or restart the equipment or service should be provided to
allow users to utilize alternative available means of interacting with ICT equipment or services and to select
accessibility related settings.
It is important for users to be able to deselect different means of interaction as well as to select them.
EXAMPLE 1 The user is allowed to use a keyboard instead of a mouse to control a screen pointer.
EXAMPLE 2 The user is allowed to select a colour scheme that does not conflict with his/her colour-blindness.
EXAMPLE 3 The user is able to separately adjust the volume on the speaker and on the microphone of a system.
EXAMPLE 4 The user is allowed to adjust physical operational functions, including distances and pressures used by a
tactile input device.
EXAMPLE 5 Input from a touch screen is turned off to avoid inadvertent contact by a user who uses a finger to help
read the contents of the screen and the functionality normally performed by the touch screen is performed by some other
input method.
EXAMPLE 6 An assistive technology can easily be activated or deactivated by a keyboard command that is always
available to the user.
ISO 9241-20:2008(E)
7.1.6 Returning to default configuration
A method that does not require users to reconfigure or restart the equipment or service should be provided to
allow users to reset ICT equipment or a service to its default configuration.
This is especially important for ICT equipment and services that are intended to be shared between multiple
users.
7.1.7 Saving and retrieving customized configurations
Where possible, a means should be provided to save and retrieve a user's customized confi
...