Web Accessibility Guidelines


Web Accessibility Guidelines

(a) A text equivalent for every non-text element shall be provided (e.g., via "alt", "longdesc", or in element content).

  • Every image, applet, embedded media, plug-in, etc. that conveys content has equivalent alternative text (altlongdesc, or in the element context).
  • The alternative text succinctly describes the content conveyed by the element, without being too verbose (for simple objects) or too vague (for complex objects).
  • Complex graphics (graphs, charts, etc.) are accompanied by equivalent text, either through a description in the body of the page, a link to a description on a separate page, and/or the longdesc attribute. [See Note 1]
  • Images that have a function (images within links, image buttons, and image map areas) have alternative text which describes the associated function.
  • Decorative graphics are CSS background images or have null/empty alt values (alt=""). Images with text alternatives in element content are given empty alt text to avoid redundancy.
  • Transcripts are provided for audio content.

(b) Equivalent alternatives for any multimedia presentation shall be synchronized with the presentation.

  • Video files and live audio broadcasts have synchronized captions.
  • Content presented through video, but not through audio is provided in an audio description track.

(c) Web pages shall be designed so that all information conveyed with color is also available without color, for example from context or markup.

  • Color is not used solely to convey important information.
  • Sufficient contrast is provided.

(d) Documents shall be organized so they are readable without requiring an associated style sheet.

  • Style sheets may be used for layout, but the document is still readable and understandable (even if less visually appealing) when the style sheet is turned off.

(e) Redundant text links shall be provided for each active region of a server-side image map.
(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.

  • Client-side image maps are used instead of server-side image maps. Appropriate alternative text is provided for the image as well as each hot spot area.

(g) Row and column headers shall be identified for data tables.

(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.

  • Data table cells are associated with the appropriate headers using the scope or id/headers attributes.

(i) Frames shall be titled with text that facilitates frame identification and navigation.

  • Each frame is given a title that describes the frame's purpose or content.

(j) Pages shall be designed to avoid causing the screen to flicker with a frequency greater than 2 Hz and lower than 55 Hz.

  • No element on the page flashes at a rate of 2 to 55 cycles per second, thus reducing the risk of optically-induced seizures.

(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.

  • text-only version is created only when there is no other way to make the content accessible or when it offers significant advantages over the main version for certain disability types.
  • The text-only version provides equivalent content and is up-to-date with the main version.

(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.

  • Content and functionality provided by scripting is directly accessible to assistive technologies and the keyboard. <noscript> content does not constitute a suitable alternative to inaccessible scripting.

(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).

  • A link is provided to a page where the plug-in can be downloaded.
  • All applets, scripts and plug-ins (including PDF and PowerPoint files, etc.) and the content within them are accessible to assistive technologies, or else an alternative means of accessing equivalent content is provided.

(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.

  • <input><textarea>, and <select> elements have descriptive labels.
  • Scripting of form elements does not interfere with assistive technologies or keyboard.

(o) A method shall be provided that permits users to skip repetitive navigation links.

  • A link is provided to skip over navigational menus or other lengthy lists of links. A good heading structure also facilitates navigation.

(p) When a timed response is required, the user shall be alerted and given sufficient time to indicate more time is required.

  • The user has control over the timing of content changes.