Web Content Accessibility Guidelines - WCAG 2.0 AA
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Section 508 Electronic and Information Technology Standards
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Examples
Below are portions of the standards related to Web-based intranet and internet information and applications from § 1194.22 of Section 508. Examples for each section are indicated in italics to illustrate the requirements. We wish to thank the Web Accessibility Center of Ohio State University (http://wac.osu.edu) for the examples.
(a) A text equivalent for every non-text element shall be provided (e.g., via "alt," "longdesc," or in element content).
Examples:
Non-text elements (images, java applets, flash files, video files, audio files, plug-ins, etc.) have alt tag descriptions that convey the purpose or intended meaning of the object (e.g., alt tags for images used as links describe the link destination).
Complex graphics that summarize information (graphs, charts, tables, etc.) are accompanied by text conveying the information providing a meaningful narrative of the information.
Decorative graphics with no other function have empty alt descriptions (alt= ""), not missing alt descriptions.
When descriptions are lengthy or refer to other resources or sites, a longer description will be made available using a link or supported "longdesc."
(b) Equivalent alternatives for any multimedia presentation shall be synchronized with the presentation.
Examples:
Multimedia files posted to a department page have synchronized captions.
A Web page supporting an on-campus course presents multimedia files and provides a separate statement about requesting captioning and the instructor/department has a letter from the Disability Resource Center outlining the time frame and various responsibilities for providing captioning.
(c) Web pages shall be designed so that all information conveyed with color is also available without color, for example from context or markup.
Example:
If color is used to convey information, alternative indicators such as an asterisk (*), are used in conjunction.
(d) Documents shall be organized so they are readable without requiring an associated style sheet.
Examples:
When a document is rendered without associated style sheets, it must still be possible to read the document.
Provide a text equivalent for any important image or text generated by style sheets (e.g., via the “background-image," “list-style," or “content" properties).
Note: WCAG recommends using style sheets to control layout and presentation. This method is strongly preferred over the use of tables due to wider compatibility with end-user devices.
(e) Redundant text links shall be provided for each active region of a server-side image map.
Example:
Separate text links are provided outside of the server-side image map that links to the same content that image map hot spots access.
(f) Client-side image maps shall be provided instead of server-side image maps except where the regions cannot be defined with an available geometric shape.
Example:
Use standard HTML client-side image maps with appropriate alt tags for the image and hot spots.
(g) Row and column headers shall be identified for data tables.
Examples:
Tables used only for layout do not have header rows or columns.
In data tables, column and row headers are identified using the <th> tag.
(h) Markup shall be used to associate data cells and header cells for data tables that have two or more logical levels of row or column headers.
Example:
Table cells are associated with the appropriate headers (e.g., id, headers, scope, and/or axis HTML attributes).
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Example:
Each frame has a title that describes its purpose or the type of information contained within the frame.
(j) Pages shall be designed to avoid causing the screen to flicker with a frequency greater than 2 Hz and lower than 55 Hz.
(k) A text-only page, with equivalent information or functionality, shall be provided to make a web site comply with the provisions of this part, when compliance cannot be accomplished in any other way. The content of the text-only page shall be updated whenever the primary page changes.
Examples:
A text-only page is acceptable when there is no other way to make the content accessible or when it offers significant advantages for ease of navigation.
The content for primary and text-only pages should be updated simultaneously. This process can be done using a common database to generate content for multiple versions of the same site.
Instead of static alternative pages, set up server-side scripts which generate accessible versions of a page on demand.
Text-only pages must be the functional equivalent to primary pages (e.g., provides alternatives for applets, scripts, plug-ins, and similar applications that are not directly accessible).
"Text-only" and "accessible" are not synonymous; designers must incorporate all of the above standards when designing text-only pages.
(l) When pages utilize scripting languages to display content, or to create interface elements, the information provided by the script shall be identified with functional text that can be read by assistive technology.
Examples:
- Within scripts, information is text-based or a text alternative is provided.
- All scripts (JavaScript, pop-up menus, etc.) work with keyboard-accessible alternatives (either within or outside of the script) that provide equivalent functionality.
(m) When a web page requires that an applet, plug-in, or other application be present on the client system to interpret page content, the page must provide a link to a plug-in or applet that complies with § 1194.21(a) through (l).
Examples:
- When applets, plug-ins, or applications (Java applets, JavaScripts, Acrobat PDF files, or PowerPoint files) are not accessible to assistive technologies you must provide an alternative means of accessing the content within the applications (e.g., a mirror text file for a PDF file).
- When an applet, plug-in, or application is utilized, you must provide a link to an accessible page where the plug-in can be downloaded.
(n) When electronic forms are designed to be completed on-line, the form shall allow people using assistive technology to access the information, field elements, and functionality required for completion and submission of the form, including all directions and cues.
Examples:
- Form controls have text labels adjacent to them and keyboard access to control functionality.
- Form elements have labels associated with them in the markup (e.g., the “id," “for," or “label," HTML elements).
- Dynamic HTML scripting of the form does not interfere with assistive technologies.
(o) A method shall be provided that permits users to skip repetitive navigation links.
Example:
- A link is provided to skip over lengthy lists of links (e.g., navigational menus).
(p) When a timed response is required, the user shall be alerted and given sufficient time to indicate more time is required.
Example:
- Do not automatically forward, refresh, or otherwise alter pages unless you provide the user with a method to adjust the timing of these content changes.
Additional Recommendations
- It is recommended that a variety of Web browsing software (including text-only and voice output browsers), workstations, and evaluation tools be used to test access to Web pages. Any University college, school, department, program, or unit should use this guidance when purchasing new forms of electronic and information technologies.