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|W3 Accessibility Guidelines|
Why are There Accessibility Guidelines?
According to the W3 Consortium"s Web Accessibility Initiative (WAI):
"These guidelines explain how to make Web content accessible to people with disabilities. The
guidelines are intended for all Web content developers (page authors and site designers) and for
developers of authoring tools. The primary goal of these guidelines is to promote accessibility.
However, following them will also make Web content more available to all users, whatever user
agent they are using (e.g., desktop browser, voice browser, mobile phone, automobile-based
personal computer, etc.) or constraints they may be operating under (e.g., noisy surroundings,
under- or over-illuminated rooms, in a hands-free environment, etc.). Following these guidelines
will also help people find information on the Web more quickly. These guidelines do not
discourage content developers from using images, video, etc., but rather explain how to make
multimedia content more accessible to a wide audience."
W3 Web Content Accessibility Guidelines
In brief, the W3 Web Content Accessibility Guidelines are:
- Provide equivalent alternatives to auditory and visual content.
- Don't rely on color alone.
- Use markup and style sheets and do so properly.
- Clarify natural language usage.
- Create tables that transform gracefully.
- Ensure that pages featuring new technologies transform gracefully.
- Ensure user control of time-sensitive content changes.
- Ensure direct accessibility of embedded user interfaces.
- Design for device-independence.
- Use interim solutions.
- Use W3C technologies and guidelines.
- Provide context and orientation information.
- Provide clear navigation mechanisms.
- Ensure that documents are clear and simple.
The Guidelines explain what each of these means, with examples.
Taken from the W3 page:
Each checkpoint has a priority level assigned by the Working
Group based on the checkpoint's impact on accessibility. Items in the Priority One section must be satisfied or else some people will find it impossible to access information in the document. The Priority 2 level items should be satisfied or many people will have significant barriers to accessing content. Satisfying Priority 3 level items will improve access to web documents.
Priority 1 checkpoints
In General (Priority 1)
- 1.1 Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ascii art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video.
- 2.1 Ensure that all information conveyed with color is also available without color, for example from context or markup.
- 4.1 Clearly identify changes in the natural language of a document's text and any text equivalents (e.g., captions).
- 6.1 Organize documents so they may be read without style sheets. For example, when an HTML document is rendered without associated style sheets, it must still be possible to read the document.
- 6.2 Ensure that equivalents for dynamic content are updated when the dynamic content changes.
- 7.1 Until user agents allow users to control flickering, avoid causing the screen to flicker.
- 14.1 Use the clearest and simplest language appropriate for a site's content.
And if you use images and image maps (Priority 1)
- 1.2 Provide redundant text links for each active region of a server-side image map.
- 9.1 Provide client-side image maps instead of server-side image maps except where the regions cannot be defined with an available geometric shape.
And if you use tables (Priority 1)
- 5.1 For data tables, identify row and column headers.
- 5.2 For data tables that have two or more logical levels of row or column headers, use markup to associate data cells and header cells.
And if you use frames (Priority 1)
- 12.1 Title each frame to facilitate frame identification and navigation.
And if you use applets and scripts (Priority 1)
- 6.3 Ensure that pages are usable when scripts, applets, or other programmatic objects are turned off or not supported. If this is not possible, provide equivalent information on an alternative accessible page.
And if you use multimedia (Priority 1)
- 1.3 Until user agents can automatically read aloud the text equivalent of a visual track, provide an auditory description of the important information of the visual track of a multimedia presentation.
- 1.4 For any time-based multimedia presentation (e.g., a movie or animation), synchronize equivalent alternatives (e.g., captions or auditory descriptions of the visual track) with the presentation.
And if all else fails (Priority 1)
- 11.4 If, after best efforts, you cannot create an accessible page, provide a link to an alternative page that uses W3C technologies, is accessible, has equivalent information (or functionality), and is updated as often as the inaccessible (original) page.
Priority 2 checkpoints
In General (Priority 2)
- 2.2 Ensure that foreground and background color combinations provide sufficient contrast when viewed by someone having color deficits or when viewed on a black and white screen. [Priority 2 for images, Priority 3 for text].
- 3.1 When an appropriate markup language exists, use markup rather than images to convey information.
- 3.2 Create documents that validate to published formal grammars.
- 3.3 Use style sheets to control layout and presentation.
- 3.4 Use relative rather than absolute units in markup language attribute values and style sheet property values.
- 3.5 Use header elements to convey document structure and use them according to specification.
- 3.6 Mark up lists and list items properly.
- 3.7 Mark up quotations. Do not use quotation markup for formatting effects such as indentation.
- 6.5 Ensure that dynamic content is accessible or provide an alternative presentation or page.
- 7.2 Until user agents allow users to control blinking, avoid causing content to blink (i.e., change presentation at a regular rate, such as turning on and off).
- 7.4 Until user agents provide the ability to stop the refresh, do not create periodically auto-refreshing pages.
- 7.5 Until user agents provide the ability to stop auto-redirect, do not use markup to redirect pages automatically. Instead, configure the server to perform redirects.
- 10.1 Until user agents allow users to turn off spawned windows, do not cause pop-ups or other windows to appear and do not change the current window without informing the user.
- 11.1 Use W3C technologies when they are available and appropriate for a task and use the latest versions when supported.
- 11.2 Avoid deprecated features of W3C technologies.
- 12.3 Divide large blocks of information into more manageable groups where natural and appropriate.
- 13.1 Clearly identify the target of each link.
- 13.2 Provide metadata to add semantic information to pages and sites.
- 13.3 Provide information about the general layout of a site (e.g., a site map or table of contents).
- 13.4 Use navigation mechanisms in a consistent manner.
And if you use tables (Priority 2)
- 5.3 Do not use tables for layout unless the table makes sense when linearized. Otherwise, if the table does not make sense, provide an alternative equivalent (which may be a linearized version).
- 5.4 If a table is used for layout, do not use any structural markup for the purpose of visual formatting.
And if you use frames (Priority 2)
- 12.2 Describe the purpose of frames and how frames relate to each other if it is not obvious by frame titles alone.
And if you use forms (Priority 2)
- 10.2 Until user agents support explicit associations between labels and form controls, for all form controls with implicitly associated labels, ensure that the label is properly positioned.
- 12.4 Associate labels explicitly with their controls.
And if you use applets and scripts (Priority 2)
- 6.4 For scripts and applets, ensure that event handlers are input device-independent.
- 7.3 Until user agents allow users to freeze moving content, avoid movement in pages.
- 8.1 Make programmatic elements such as scripts and applets directly accessible or compatible with assistive technologies [Priority 1 if functionality is important and not presented elsewhere, otherwise Priority 2.]
- 9.2 Ensure that any element that has its own interface can be operated in a device-independent manner.
- 9.3 For scripts, specify logical event handlers rather than device-dependent event handlers.
Priority 3 checkpoints
In General (Priority 3)
- 4.2 Specify the expansion of each abbreviation or acronym in a document where it first occurs.
- 4.3 Identify the primary natural language of a document.
- 9.4 Create a logical tab order through links, form controls, and objects.
- 9.5 Provide keyboard shortcuts to important links (including those in client-side image maps), form controls, and groups of form controls.
- 10.5 Until user agents (including assistive technologies) render adjacent links distinctly, include non-link, printable characters (surrounded by spaces) between adjacent links.
- 11.3 Provide information so that users may receive documents according to their preferences (e.g., language, content type, etc.)
- 13.5 Provide navigation bars to highlight and give access to the navigation mechanism.
- 13.6 Group related links, identify the group (for user agents), and, until user agents do so, provide a way to bypass the group.
- 13.7 If search functions are provided, enable different types of searches for different skill levels and preferences.
- 13.8 Place distinguishing information at the beginning of headings, paragraphs, lists, etc.
- 13.9 Provide information about document collections (i.e., documents comprising multiple pages.).
- 13.10 Provide a means to skip over multi-line ASCII art.
- 14.2 Supplement text with graphic or auditory presentations where they will facilitate comprehension of the page.
- 14.3 Create a style of presentation that is consistent across pages.
And if you use images and image maps (Priority 3)
- 1.5 Until user agents render text equivalents for client-side image map links, provide redundant text links for each active region of a client-side image map.
And if you use tables (Priority 3)
- 5.5 Provide summaries for tables.
- 5.6 Provide abbreviations for header labels.
- 10.3 Until user agents (including assistive technologies) render side-by-side text correctly, provide a linear text alternative (on the current page or some other) for all tables that lay out text in parallel, word-wrapped columns.
And if you use forms (Priority 3)
- 10.4 Until user agents handle empty controls correctly, include default, place-holding characters in edit boxes and text areas.
Accessibility Introduction | What is Accessibility? | Why is Accessibility Important? | W3 Consortium Guidelines | Section 508 Standards | ADA and Disabilities Guidelines | Accessibility Audit | References and Resources | Usability Introduction | InfoQuest!
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Last updated: November 4, 2001
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