For each time limit that is set by the content, the user can turn off, adjust, or extend the limit. (Level A)

Rationale

The purpose of this checkpoint is to ensure users with disabilities have adequate time to interact with content when possible. People with disabilities may require additional time to read content or perform functions such as completing online forms. When faced with time-dependent functions, users with low vision, dexterity impairments or cognitive limitations may have difficulty performing the required action before reaching a time limit, making the service potentially inaccessible to them.

A time limit includes any process that occurs (without user initiation) after a set amount of time or on a periodic basis. Examples include partial or full updates of content such as page refreshes, changes to content, or the expiration of a "window of opportunity" for user input requests. Time limits also include content that is advancing or updating at a rate beyond the user's ability to read and/or understand (e.g., animated, moving or scrolling content that introduces a time limit on the user's ability to read content).

By designing functions that are not time-dependent, you can help people with disabilities complete these functions. When a time limit is required, one of the following options must be provided. They are in order of preference, with the first item being the best option:

  1. Turn off: The user is allowed to turn off the time limit before encountering it; or
  2. Adjust: The user is allowed to adjust the time limit before encountering it over a wide range that is at least ten times the length of the default setting; or
  3. Extend: The user is warned before time expires and given at least 20 seconds to extend the time limit with a simple action (for example, "press the space bar"), and the user is allowed to extend the time limit at least ten times.

Real-time Exception: This checkpoint does not apply if the time limit is a required part of a real-time event (for example, an auction), and no alternative to the time limit is possible.
Essential Exception: This checkpoint does not apply if the time limit is essential and extending it would invalidate the activity.
20 Hour Exception: This checkpoint does not apply if the time limit is longer than 20 hours.

Refer to Understanding SC 2.2.1 for more information (external link to WCAG).

Development Techniques

Review the General techniques as well as other tabs applicable to your technology.  Prioritize the use of technology-specific techniques, and implement the General techniques as needed. You are always required to find, understand and implement accessible code techniques to meet the checkpoint. The documented techniques and supplements are not exhaustive; they illustrate acceptable ways to achieve the spirit of the checkpoint. If numbered, techniques are in order of preference, with recommended techniques listed first. Where used, IBM information that complements the WCAG techniques is indicated as supplemental.

General techniques

Instructions: Select the situation below that matches your content. Any item in the described situation represents a technique that is deemed sufficient for meeting this checkpoint. Where numbered, techniques are ordered from most to least preferred. Ensure you review WCAG Common Failures to avoid development mistakes.

Situation A: If there are session time limits:

  1. G198: Providing a way for the user to turn the time limit off
  2. G133: Providing a checkbox on the first page of a multipart form that allows users to ask for longer session time limit or no session time limit
  3. Provide a simple user action to extend time (supplement)

Situation B: If a time limit is controlled by a script on the page:

  1. G198: Providing a way for the user to turn the time limit off
  2. G180: Providing the user with a means to set the time limit to 10 times the default time limit
  3. Provide a simple user action to extend time (supplement)

Situation C: If there are time limits on reading:

  1. G198: Providing a way for the user to turn the time limit off
  2. G4: Allowing the content to be paused and restarted from where it was paused

Situation D: If time limits can be avoided:

General supplements

The following techniques, examples and comments provide additional information beyond that available in the WCAG techniques.

Provide a simple user action to extend time

Give the user the option of extending the timeout with a simple action. For example, a bank application with a secure login may have a default timeout of 10 minutes if no action is detected on the screen. Once that 10 minutes is up, a pop-up should appear on the screen notifying the user that the session is about to expire. The user is given sufficient time to extend the timeout with a simple action, such as activating an "I need more time" button.

Do not impose a timed response

  • Where feasible, consider a non-timed response in the design. Designing functions that are not time-dependent will help people with disabilities succeed at completing these functions.
  • Do not impose a timed response for important messages. Instead, display the message until the user acknowledges it.

Web (HTML, ARIA, CSS) techniques

Instructions: In addition to the General techniques, items in this section represent  techniques or combination of techniques deemed sufficient to address particular situations.

Situation B: If a time limit is controlled by a script on the page:

Situation C: If there are time limits on reading:

Web supplements

The following techniques, examples and comments provide additional information beyond that available in the WCAG techniques.

SCR16: Providing a script that warns the user a time limit is about to expire

In the description for SCR16, WCAG suggests a 20 second warning before the time limit expires. Given the checkpoint is concerned with giving users adequate time to respond, this 20-second limit seems arbitrary and unreasonable. By providing a dialog box that appears 2-3 minutes before the page access time limit expires, the user has a more reasonable chance to extend the time by selecting a button.

Mobile Native (iOS) techniques

There are no specific Mobile Native iOS techniques for this checkpoint. Refer to the General techniques section.

Eclipse techniques

There are no specific Eclipse techniques for this checkpoint. Refer to the General techniques section.

Windows-based (MSAA+IA2) techniques

There are no specific Windows-based (MSAA+IA2) techniques for this checkpoint. Refer to the General techniques section.


Most links in this checklist reside outside ibm.com at the Web Content Accessibility Guidelines (WCAG) 2.0. W3C Recommendation 11 December 2008: http://www.w3.org/TR/WCAG20/

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