Until user agents... clauses in WAI Technical Recommendations

Note: with the exception of the navigation map which follows this text, all links are external links, linking to either WCAG 1.0, the Techniques for Web Content Accessibility 1.0, and the apparently no longer actively maintained WAI Reference document, User Agent Support for WCAG 1.0

Definition of "Until user agents..."

Source: Web Content Accessibility Guidelines, version 1.0
(http://www.w3.org/TR/WCAG10/wai-pageauth.html#until-user-agents)

Until user agents ...
In most of the checkpoints, content developers are asked to ensure the accessibility of their pages and sites. However, there are accessibility needs that would be more appropriately met by user agents (including assistive technologies). As of the publication of this document, not all user agents or assistive technologies provide the accessibility control users require (e.g., some user agents may not allow users to turn off blinking content, or some screen readers may not handle tables well). Checkpoints that contain the phrase "until user agents..." require content developers to provide additional support for accessibility until most user agents readily available to their audience include the necessary accessibility features.

Note. The W3C WAI Web site provides information about user agent support for accessibility features. (refer to [WAI-UA-SUPPORT]) Content developers are encouraged to consult this page regularly for updated information.

Until User Agents... Clauses in WCAG1

Guideline 1: Provide equivalent alternatives to auditory and visual content.

Checkpoint 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. [Priority 1]
Synchronize the auditory description with the audio track as per checkpoint 1.4. Refer to checkpoint 1.1 for information about textual equivalents for visual information.
Checkpoint 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. [Priority 3]
Refer also to checkpoint 1.2 and checkpoint 9.1.

Guideline 7. Ensure user control of time-sensitive content changes.

Ensure that moving, blinking, scrolling, or auto-updating objects or pages may be paused or stopped.

Some people with cognitive or visual disabilities are unable to read moving text quickly enough or at all. Movement can also cause such a distraction that the rest of the page becomes unreadable for people with cognitive disabilities. Screen readers are unable to read moving text. People with physical disabilities might not be able to move quickly or accurately enough to interact with moving objects.

Note. All of the following checkpoints involve some content developer responsibility, until user agents provide adequate feature control mechanisms.

Checkpoints for Guideline 7:

Checkpoint 7.1 Until user agents allow users to control flickering, avoid causing the screen to flicker. [Priority 1]

Note. People with photosensitive epilepsy can have seizures triggered by flickering or flashing in the 4 to 59 flashes per second (Hertz) range with a peak sensitivity at 20 flashes per second as well as quick changes from dark to light (like strobe lights).
Checkpoint 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). [Priority 2]
Checkpoint 7.3 Until user agents allow users to freeze moving content, avoid movement in pages. [Priority 2]
When a page includes moving content, provide a mechanism within a script or applet to allow users to freeze motion or updates. Using style sheets with scripting to create movement allows users to turn off or override the effect more easily.
Checkpoint 7.4 Until user agents provide the ability to stop the refresh, do not create periodically auto-refreshing pages. [Priority 2]
For example, in HTML, don't cause pages to auto-refresh with "HTTP-EQUIV=refresh" until user agents allow users to turn off the feature.
Checkpoint 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. [Priority 2]
Note. The BLINK and MARQUEE elements are not defined in any W3C HTML specification and should not be used.

Guideline 10. Use interim solutions.

Use interim accessibility solutions so that assistive technologies and older browsers will operate correctly.

For example, older browsers do not allow users to navigate to empty edit boxes. Older screen readers read lists of consecutive links as one link. These active elements are therefore difficult or impossible to access. Also, changing the current window or popping up new windows can be very disorienting to users who cannot see that this has happened.

Note. The following checkpoints apply until user agents (including assistive technologies) address these issues. These checkpoints are classified as "interim", meaning that the Web Content Guidelines Working Group considers them to be valid and necessary to Web accessibility as of the publication of this document. However, the Working Group does not expect these checkpoints to be necessary in the future, once Web technologies have incorporated anticipated features or capabilities.

Checkpoints for Guideline 10:

Checkpoint 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. [Priority 2]
For example, in HTML, avoid using a frame whose target is a new window.
Checkpoint 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. [Priority 2]
The label must immediately precede its control on the same line (allowing more than one control/label per line) or be in the line preceding the control (with only one label and one control per line). Refer also to checkpoint 12.4.
Checkpoint 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. [Priority 3]
Note. Please consult the definition of linearized table. This checkpoint benefits people with user agents (such as some screen readers) that are unable to handle blocks of text presented side-by-side; the checkpoint should not discourage content developers from using tables to represent tabular information.
Checkpoint 10.4 Until user agents handle empty controls correctly, include default, place-holding characters in edit boxes and text areas. [Priority 3]
For example, in HTML, do this for TEXTAREA and INPUT.
Checkpoint 10.5 Until user agents (including assistive technologies) render adjacent links distinctly, include non-link, printable characters (surrounded by spaces) between adjacent links. [Priority 3]

Guideline 13: Provide clear navigation mechanisms.

Checkpoints for Guideline 13

Checkpoint 13.6 Group related links, identify the group (for user agents), and, until user agents do so, provide a way to bypass the group. [Priority 3]

Related Resources

this document hand constructed by Gregory J. Rosmaita for the consideration of the Web Accessibility Initiative (WAI).

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