上海时时乐上Web Accessibility Initiative (WAI)         logo

WAI: Strategies, guidelines, resources to make the Web accessible to people with disabilities

上海时时乐赢遍天下:Fact Sheet for "Web Content Accessibility Guidelines 1.0"

上海时时乐上 www.tf5x.com.cn WCAG 2.0 was published in December 2008, and is recommended over WCAG 1.0. See Web Content Accessibility Guidelines (WCAG) Overview.

Published May 1999

This "Frequently Asked Questions" (FAQ) page provides background on W3C's "Web Content Accessibility Guidelines 1.0" Recommendation, released on May 5, 1999. The document address is //www.tf5x.com.cn/TR/1999/WAI-WEBCONTENT-19990505

Contents

  1. What are the Web Content Accessibility Guidelines?
  2. What are the "priorities" and "conformance levels," and how does one use the logos?
  3. Who are these guidelines written for?
  4. Why are these guidelines needed? Why are they important?
  5. How many people are affected by issues of Web accessibility?
  6. What are some examples of common barriers on Web pages?
  7. How will these guidelines affect usability & appearance of sites for non-disabled users?
  8. Why don't the guidelines recommend using text-only pages?
  9. Does it cost more to make a site accessible?
  10. Are some authoring tools better for making accessible sites than others?
  11. Will these guidelines become a requirement? Are there legal consequences for not making a site accessible?
  12. What supporting resources are available for using these guidelines?
  13. Are there tools that can help me? Can I test the accessibility of my site?
  14. What is the most important thing to understand in terms of making a site accessible?
  15. Will the guidelines be stable across evolving Web technologies?
  16. Who has been involved in developing these guidelines?
  17. What Web sites are already using these guidelines? Can I see examples?
  18. How are these guidelines related to the other W3C/WAI guidelines?
  19. How does one learn more about Web accessibility and the WAI?
  20. What is the role of the W3C in Web accessibility?


1. What are the "Web Content Accessibility Guidelines"?

The "Web Content Accessibility Guidelines 1.0" are a W3C specification providing guidance on accessibility of Web sites for people with disabilities. They have been developed by the W3C's Web Accessibility Initiative. The specification contains fourteen guidelines which are general principles of accessible design. Each guideline is associated with one or more checkpoints describing how to apply that guideline to particular features of Web pages. An appendix to the guidelines, "List of Checkpoints for the Web Content Accessibility Guidelines 1.0" presents the checkpoints sorted by priority for easy reference. These guidelines not only make pages more accessible to people with disabilities, but also have the side benefit of making pages more accessible to all users, or to users using different browsers or one of the emerging handheld or voice-based computers.

2. What are the "priorities" and "conformance levels," and how does one use the logos?

Each checkpoint is assigned one of three priority levels. Priority one is for checkpoints that a developer must satisfy otherwise some groups of people will be unable to access information on a site; priority two a developer should satisfy or else it will be very difficult to access information; priority three a developer may satisfy otherwise, some people will find it difficult to access information.

The specification defines three "conformance levels" to facilitate reference by other organizations. Conformance level "Single-A" includes priority one checkpoints; "Double-A" includes priority one and two; "Triple-A" includes priority one, two and three.

For those whose pages follow the guidelines, logos are available which can be placed on their site to show conformance. See question 13 for information on partially automated checkers to help in assessing sites.

3. Who are these guidelines written for?

The guidelines are written for a variety of audiences--people who are designing Web sites; people who are checking existing Web sites for accessibility; organizations that wish to require a given level of accessibility for their Web sites; and others who are interested in ensuring that people with disabilities can access information on the Web.

4. Why are these guidelines needed? Why are they important?

People with different kinds of disabilities can experience difficulty using the Web due to a combination of barriers in the information on Web pages, and barriers in the "user agents" (browsers, multimedia players, or assistive technologies such as screen readers or voice recognition).

The Web Content Accessibility Guidelines deal specifically with reduction of barriers on Web pages. For some people with disabilities, barriers can mean lack of access to information needed for educational programs; lack of access to employment-related information or workplace intranets; lack of access to information on civic activities or programs; inability to participate in E-Commerce; or prevent lack of access to information on the Web in general.

5. How many people are affected by issues of Web accessibility?

The percentage of people with disabilities in many populations is between 10% and 20%. Not all disabilities affect access to information technologies such as the Web (for instance, difficulty walking, or a heart condition, would not affect Web access) but many do.

Just as with other parts of the population, not all people with disabilities have access to the Web. But the number of people using the Web is steadily increasing, and for people with disabilities access to this technology is sometimes even more critical than for the general population which may have an easier time accessing traditional sources of information such as print media.

6. What are examples of some common barriers on Web pages?

These guidelines address barriers in Web pages which people with physical, visual, hearing, and cognitive/neurological disabilities may encounter. Common accessibility problems on Web sites include: images without alternative text; lack of alternative text for imagemap hot-spots; misleading use of structural elements on pages; uncaptioned audio or undescribed video; lack of alternative information for users who cannot access frames or scripts; tables that are difficult to decipher when linearized; or sites with poor color contrast.

7. How will these guidelines affect usability and appearance of sites for non-disabled users?

Accessible Web sites can be just as creatively designed as inaccessible sites. The Web Content Accessibility Guidelines address how to make a large variety of Web features accessible, rather than recommending that sites be dull or boring. The goal is to ensure that all kinds of Web sites, including multimedia, work well for all users. In general, accessible Web sites don't need to be designed to be very different. They just need to be designed to be flexible; flexible so that users can operate them in different ways (with keyboard and mouse), and flexible so that they transform gracefully into intelligible and useful pages if particular technologies are not supported, or cannot be used by particular users or browsers.

Many features of the guidelines will actually improve usability of Web sites for non-disabled users, by ensuring that sites are more easily navigable, and that they can be accessed through a variety of different kinds of devices rather than only a traditional graphical desk-top browser.

8. Why don't the guidelines recommend using text-only pages?

Text-only pages should not be necessary to ensure accessibility of Web pages that follow the "Web Content Accessibility Guidelines," except in very rare cases. In fact, text-only pages are frequently counterproductive to accessibility since they tend to be kept less up-to-date than "primary pages," or in some cases leave out information that is on primary pages.

Many sites that have made a commitment to accessibility in the past have used text-only pages as a solution; however, by following these guidelines it should be unnecessary in almost all cases, or even inadvisable, to set up and maintain a separate set of text-only pages.

9. Does it cost more to make a site accessible?

Designing a new site to be accessible should not add significantly to development cost. Some aspects of accessibility, such as use of style sheets, can actually reduce the costs of maintaining or updating sites, and this benefit should increase over time as style sheets are more evenly implemented in browsers and available as an authoring strategy in authoring tools.

For existing sites, the ease or difficulty of making sites accessible depends on a variety of factors, including the size of a site, the complexity of a site, and the authoring tool that was used to make a site. Periodic upgrades or reviews of sites can be good opportunities to review the accessibility of sites. When compared with the broader audience that a site is available to, and the greater usability for other users as well, accessible sites can be cost-effective.

10. Are some authoring tools better for making accessible sites than others?

Key features to look for in Web authoring tools include production of valid HTML and CSS, support for key accessibility features in those specifications, and user-configurable prompting, alerts, validation and help for accessible authoring. Look for this information in product literature, or enquire of the authoring tool developer. For more information on authoring tool accessibility, see the W3C Authoring Tool Accessibility Guidelines.

11. Will these guidelines become a requirement? Are there legal consequences for not making accessible pages?

These guidelines are a specification developed by the W3C, an international, vendor-neutral industry consortium, and have been developed under W3C process. W3C is not a legislative body and the Web Content Accessibility Guidelines specification is not a regulation. The guidelines may be informally or formally adopted by different kinds of organizations to clarify what level of accessibility that organization requires for particular Web sites. If you would like to learn more about specific laws or policies in different countries which have bearing on accessibility requirements for Web sites, some of these are available in the policy references section of the WAI site. Please contact the relevant legal authority for more details on obligations and/or enforcement.

12. What supporting resources are available for using these guidelines?

The two most important documents for using the guidelines are linked directly from the guidelines themselves. The "List of Checkpoints," an appendix to the guidelines, groups the checkpoints by priority and type for ease of reference. The "Techniques" document explains how to mark-up different accessibility features in various mark-up languages.

In addition, the Web Accessibility Initiative International Program Office's work includes education and outreach activities. As a result, WAI frequently adds resources which may be helpful in training, reference, or on-line instruction. There is a very short "Quick Tips" reference card available in a business-card sized format, providing reminders of key concepts in the guidelines. There are technical references on the accessibility features in HTML and CSS. There is a reference list of browsers which links to information on access features of different browsers. At the time of this release WAI is developing an on-line curriculum to accompany the Web Content Accessibility Guidelines. These and more resources are available from the WAI home page.

13. Are there tools that can help me? Can I test the accessibility of my site?

There are an increasing number of tools that can help in designing or evaluating accessibility of sites. Around the time of this release, "Bobby," which is an accessibility checker developed by the Center for Applied Special Technology (CAST), will be updated to perform an automated on-line test of many of the checkpoints that are part of the "Web Content Accessibility Guidelines 1.0." Such accessibility checkers can often help with an initial identification of barriers on a site. Because no tool can perform a complete automated test of accessibility, and because false positives and false negatives are possible on some sites, claims of a particular conformance level must rely on manual checking as well. In using any evaluation tool or logo, including WAI's logos, it is important to examine what document version the tool or logo is synchronized with, and any additional information about how it is intended to be used.

Additional tools under development include tools to help retrofit sites and plug-ins to assist legacy browsers in properly rendering newer mark-up. WAI conducts working and interest groups focusing on evaluation and repair tools, and helps coordinate the efforts of developers involved in building various tools to help with accessibility.

14. What is the most important thing to understand in terms of making a site accessible?

The most important thing to understand in terms of making a site accessible is that people use the Web in very different ways. A site should therefore present information in a way that people can access it regardless of what kind of hardware or software they are using, and regardless of how they navigate through a site. Web designers cannot assume that everyone uses the same kinds of devices the same way.

15. Will the guidelines be stable across evolving Web technologies?

The Web Content Accessibility Guidelines are designed to be both forwards-compatible and backwards-compatible to the greatest extent possible within the context of evolving Web technologies. Within the document, the fourteen guidelines focus on principles of accessible design and are abstract enough to be stable over time. Each set of checkpoints associated with a particular guideline is specific to a particular feature of Web pages, but still general to a variety of mark-up and presentation languages, and therefore expected to be relatively stable over time. Certain checkpoints include the phrase "until user agents..." because, as browsers and assistive technologies such as screen readers evolve, they will be able to automatically handle certain items that currently create barriers on pages.

The separate "Techniques" document, which is not part of the normative guidelines document, is specific to individual mark-up languages, and will be updated more frequently as technologies evolve.

16. Who has been involved in developing these guidelines?

As Members in an international industry consortium, W3C 's 300+ Member organizations have had frequent opportunities to review and comment on the guidelines as they have evolved, and some Member organizations have participated directly in the Web Content Guidelines Working Group, or in the WAI Interest Group which provides on-going discussion and input to WAI working groups on Web accessibility needs and solutions. In addition W3C's Web Accessibility Initiative provides a forum for disability organizations, accessibility research centers, and government to participate with industry representatives under W3C process. Participation in the Web Content Accessibility Guidelines has included representation from all of these areas, with extensive international participation. As a W3C Recommendation, this specification has undergone formal review by W3C Member organizations and all comments raised have been addressed.

17. What Web sites are already using these guidelines? Can I see examples?

The release of the Web Content Accessibility Guidelines as a Recommendation signified its stabilization. WAI has received commitments from a variety of organizations who plan for their sites to conform with the guidelines. Many sites are expressing interest in conforming at the "Double-A" level , meaning all priority one and two checkpoints. As sites implement the guidelines, WAI will provide links to a sampling of sites where there is a commitment to maintain at least a Double-A conformance rating. Please visit the WAI home page for more information.

18. How are these guidelines related to the other WAI guidelines, and other WAI work?

The Web Content Accessibility Guidelines address one aspect of the accessibility equation -- how accessible is the content on a site. A second part of the equation is the accessibility of browsers, which WAI is addressing that through a set of "User Agent Accessibility Guidelines." A third part of the equation is accessibility of the authoring tools used to develop sites, which is addressed through the "Authoring Tool Accessibility Guidelines." If authoring tools become more supportive of accessible authoring, it will greatly facilitate the accessible content creation.

In addition to guidelines development, WAI also works internally within W3C on ensuring that the technologies of the Web, such as HTML, CSS, SMIL, XML, DOM, etc., support accessibility. WAI coordinates with other organizations to develop tools which can assist in evaluation, and retrofitting pages and providing proxy solutions to support accessibility. WAI has an active education and outreach effort, and some activity coordinating with research and development which can affect future Web access.

19. How does one learn more about accessibility and WAI?

The WAI home page, at //www.tf5x.com.cn/WAI, has up-to-date information on all the resources of the Web Accessibility Initiative. There are resource and reference areas which are updated frequently; lists of upcoming events; links to WAI's many working groups and interest groups; and an overall interest group for general discussion of Web accessibility issues. There are a great many organizations doing excellent work in the area of Web accessibility, and many of these participate in WAI. WAI's reference links provide a start to finding many of these organizations.

20. What is the role of W3C in Web accessibility?

上海时时乐上's mission is to promote the evolution and interoperability of the Web. The Web Accessibility Initiative, hosted by the W3C, is an essential aspect of the work needed to promote the universality of the Web.


About the Web Accessibility Initiative

W3C's Web Accessibility Initiative (WAI), in partnership with organizations around the world, is pursuing accessibility of the Web through five complementary activities: ensuring that the core technologies of the Web support accessibility; developing guidelines for page authoring, user agents, and authoring tools; developing evaluation and repair tools for accessibility; conducting education and outreach; and tracking research and development that can affect the future accessibility of the Web. The WAI International Program Office is supported in part by funding from the U.S. National Science Foundation, U.S. Department of Education's National Institute on Disability and Rehabilitation Research, European Commission's DG XIII Telematics Applications Programme for Disabled and Elderly, the Government of Canada, IBM, Lotus Development Corporation, Microsoft Corporation, and NCR. For more information on the Web Accessibility Initiative, see //www.tf5x.com.cn/WAI

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