THE FUTURE LOOKS BRIGHT: INTERNATIONAL STANDARDS FOR ACCESSIBLE SOFTWARE
University of Saskatchewan
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Recent work in International Standards has led to the development of
three standards on software accessibility: ISO 9241-20, ISO 9241-171, and ISO/IEC 24756. We discuss the benefits provided by these standards, outline their content, and encourage their use.
David Fourney, Department of Computer Science, University of Saskatchewan, Saskatoon, Saskatchewan, Canada firstname.lastname@example.org
Jim Carter, Department of Computer Science, University of Saskatchewan, Saskatoon, Saskatchewan, Canada email@example.com
Recent work in International Standards has led to the development of three standards on software accessibility: ISO 9241-20, ISO 9241-171, and ISO/IEC 24756. This paper discusses the benefits provided by these standards and encourages their use.
International Standards play an important role in global commerce. They form an agreement that ensures a common practice is followed. Although several organizations are involved in international standards development, the International Organisation for Standardisation (ISO) is probably the most well-known.
In some countries international standards are voluntary, in others they carry the strength of law. Some international standards, such as the ISO 9000 series, have received a great amount of attention and are, on some level, at least recognizable by the general public whether they know what it is or not. Other international standards, such as ISO/IEC 10918-1 (i.e., the document that sets out the graphic format known as "JPEG" frequently used in web pages for still pictures) (ISO, 1994), are used by many without realizing it.
The upcoming publication of ISO 9241-20, ISO 9241-171, and ISO/IEC 24756 provide a major achievement in the evolution of accessible software design towards the day when it is fully assimilated and routinely considered a part of all software development.
2. ISO 9241-171 Guidance on Software Accessibility
The Human Factors and Ergonomics Society's HFES/ANSI 200 committee recognized the importance of developing accessibility standards and started work in this area in the mid 1990's. While their original draft was based on the Nordic Accessibility Guidelines (Thoren, 1998) they have gone far beyond the original set of guidelines. In 1998 the HFES/ANSI 200 committee submitted their work to date to ISO committee TC159/SC4/WG5 Software Ergonomics and Human Computer Dialogue as the basis for international work on software accessibility standardization. This led to the development and publication of ISO TS 16071 Guidance on accessibility for human computer interfaces.
International standards are typically based on empirical research, accepted best practice, or both. Often, standards developed by one country are offered as a source for an international standard. This is true of ISO 9241-171, which is based on the American HFES/ANSI 200.2 and their predecessor document ISO TS 16071.
The ISO 9241 series is a set of standards concerned with the ergonomics of computer software. Part 171 is especially concerned with the accessibility of software. An evaluation of the content of ISO TS 16071 soon after its publication suggested a number of key areas that needed further attention (Carter and Fourney, 2004). Whereas ISO TS 16071 focused on providing accessibility to people with special needs, ISO 9141-171 takes a wider "design for all" approach. The current version of ISO 9241-171 contains individual guidelines as well as guidance on complying with these guidelines.
ISO 9241-171 contains a variety of new content beyond that found in previous versions. For example, ISO 9241-171 defines accessibility as the, "usability of a product, service, environment, or facility by people with the widest range of capabilities". Many authors believe that there should be no distinction between the concepts of usability and accessibility (e.g., according to Moulton, Huyler, Hertz, & Levenson, 2002, "Accessibility is good usability."), and that the term "usability" should encompass the meaning of both terms. The ISO definition of the term "accessibility" recognizes that usability problems impact all users equally, regardless of ability and that a person with a disability is not disadvantaged to a greater extent by usability issues than a person without a disability (Thatcher et al., 2002).
This ISO definition also recognizes that accessibility cannot be seen as a "special case" of usability. The notion that if usability is about producing products and systems that are easy to use and perform the function for which they were designed, then accessible design is about producing products and systems that are usable by all persons regardless of (dis)ability is dangerous. The danger here is that a product could be "usable" without being "accessible." That is, a designer could view accessible design as "outside of" usable design and design an inaccessible product.
3. ISO 9241-20 Accessibility guidelines for information communication equipment and services
With the explicit focus of ISO 9241-171 on software accessibility, the need was recognized for a computer hardware accessibility standard. However, in advance to developing a specific hardware standard, the ISO committee on Ergonomics of Human-system Interaction (ISO TC159/SC4) decided to develop a high level systems and services standard (ISO 9241-20) that would apply to both hardware and software, without duplicating any of the content that is contained in ISO 9241-171 or that would be contained in a hardware accessibility standard.
ISO 9241-20 recognizes that accessibility is achieved and improved by serving "the widest variations within a context of use" which can be based on user characteristics, equipment characteristics, environmental characteristics, and task characteristics, and their variability. It presents a framework for accessibility that considers the characteristics and needs of users, tasks, equipment, and the environment and presents guidance relating to each of these four types of characteristics. It also presents 18 user-related, 15 equipment-related, 6 task-related, and 3 environment-related guidelines.
4. ISO/IEC 24756 Algorithmic framework for determining accessibility for individual users of interactive systems
As noted above, international standards are typically based on empirical research, accepted best practice, or both. ISO/IEC 24756, "Algorithmic framework for determining accessibility for individual users of interactive systems" (ISO & IEC, 2005) is a standard that identifies "inaccessibilities". It is based on the definition of accessibility used in ISO 9241-171 and the model proposed by Carter and Fourney (2004). ISO/IEC 24756 compares the needs and abilities of systems with users to communicate using various modalities and takes into account the environment(s) in which the user and system interact. It allows the consideration of multiple levels of system components, including: application software, operating systems, computer hardware, peripheral devices, and assistive technologies. This standard can be used to analyze existing human-computer interactions and to help evaluate the usefulness of proposed assistive technologies.
The upcoming publication of these standards is exciting. They will each provide guidance to assist developers to design their products to meet the needs of the widest number of users. This has implications for both developers who will be able to sell their products to a wider audience, and consumers with disabilities who will benefit from greater choice of products accessible to them.
Carter, J., & Fourney, D. (2004). Using a Universal Access Reference Model to identify further guidance that belongs in ISO 16071. Universal Access in the Information Society, 3 (1), 17-29. http://www.springerlink.com/link. asp?id=wdqpdu5pj0kb4q6b
International Organization for Standardization. (2002). ISO/TS 16071:2002 Ergonomics of human system interaction - Guidance on accessibility for human computer interfaces.
International Organization for Standardization, & International Electrotechnical Commission. (2005). ISO/IEC CD 24756 Information technology - Algorithmic framework for determining accessibility for individual users of interactive systems (ISO/IEC JTC 1 / SC35 Document N903).
International Organization for Standardization, & International Electrotechnical Commission. (1994). ISO/IEC 10918-1:1994 Information technology - Digital compression and coding of continuous-tone still images: Requirements and guidelines.
Moulton, G., Huyler, L., Hertz, J., & Levenson, M. (2002). Accessible technology in today's business: Case studies for success.
Thatcher, J., Waddell, C., Henry, S., Swierenga, S., Urban, M., Burks, M., Regan, B., & Bohman, P. (2002). Constructing accessibile web sites.
Thoren, C. (ed.) (1998). Nordic Guidelines for Computer Accessibility (Second Edition). Nordic Cooperation on Disability. http://trace.wisc.edu/docs/nordic_guidelines/nordic_guidelines.htm