For each time limit that is set by the content, at least one of the following is true:
- Turn off: The user is allowed to turn off the time limit before encountering it.
- 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.
- 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: 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: The time limit is essential and extending it would invalidate the activity.
- 20 Hour Exception: The time limit is longer than 20 hours.
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Rationale
The intent of this checkpoint is to ensure that users with disabilities are given adequate time to interact with Web content whenever possible. People with disabilities such as blindness, low vision, dexterity impairments, and cognitive limitations may require more time to read content or to perform functions such as filling out on-line forms. If Web functions are time-dependent, it will be difficult for some users to perform the required action before a time limit occurs. This may render the service inaccessible to them. Designing functions that are not time-dependent will help people with disabilities succeed at completing these functions. Providing options to disable time limits, customize the length of time limits, or request more time before a time limit occurs helps those users who require more time than expected to successfully complete tasks. These options are listed in the order that will be most helpful for the user. Disabling time limits is better than customizing the length of time limits, which is better than requesting more time before a time limit occurs.
Any process that happens without user initiation after a set time or on a periodic basis is a time limit. This includes partial or full updates of content (for example, page refresh), changes to content, or the expiration of a window of opportunity for a user to react to a request for input.
It also includes content that is advancing or updating at a rate beyond the user's ability to read and/or understand it. In other words, animated, moving or scrolling content introduces a time limit on a user's ability to read content.
In some cases, however, it is not possible to change the time limit (for example, for an auction or other real-time event) and exceptions are therefore provided for those cases.
Required development techniques
Compliance with this checkpoint requires all of the following techniques to be met. These techniques are defined in the WCAG 2.0 Level A Success Criterion for Guideline 2.2.1 (link resides outside of ibm.com).
1. Change default time limit: Provide a way for the user to turn off, adjust, or extend the default time limit.
Examples for General developers
1. Change default time limit: Provide a way for the user to turn off, adjust, or extend the default time limit.
To comply with this technique, at least one of the following examples must be implemented.
Example 1
Provide a way for the user to turn the time limit off. It is essential that the mechanism for turning off the time limit can be completed without a time limit itself and before the time limit for the page expires. To do this - the mechanism should be available at or near the top of the page so that it can be found and activated quickly by people with a wide range of disabilities.
An example is a page that has a listing of news headlines that automatically update every minute. At the top of the page is a link that turns off the updating.
Example 2
Provide the user with a means to set the time limit up to 10 times the default time limit. An example is a Web based email application that automatically logs users out when there has been no activity for 30 minutes. The application would include a preference that allows users to adjust the amount of time to any value.
Example 3
Provide 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. An example is a Web page that contains the first part of a five-part form. Immediately following the general instructions for completing the form is a checkbox with the label, "Allow an additional 15 minutes to complete each part of this form."
Example 4
Allow the content to be paused and restarted from where it was paused. If the user needs to pause the movement to reduce distraction or to have time to read it, they can do so, and then restart it as needed. This mechanism can be provided either through interactive controls that conform to WCAG or through keyboard shortcuts. If keyboard shortcuts are used, they must be documented.
An example is a site that contains a scrolling news banner at the top of the page. Users who need more time to read it can press the Escape key to pause the scrolling. Pressing Escape again restarts it.
Examples for Script developers
1. Change default time limit: Provide a way for the user to turn off, adjust, or extend the default time limit.
To comply with this technique, all of the following examples must be implemented.
Example 5
Provide a script that warns the user a time limit is about to expire. Provide a dialog popup box when there are 3 minutes left in the allotted time before the secure access to a Web page expires – allow the user to extend the time by clicking a button.
For a detailed example of how this can be done, please refer to the WCAG 2.0 examples for Providing a script that warns the user a time limit is about to expire (link resides outside of ibm.com).
Example 6
Use a script to scroll content, and provide a mechanism to pause it. An example would be a news ticker on the ibm.com homepage that automatically updated every 30 seconds with a news article. A script needs to be available to pause the update or scroll the content.
For a detailed example of how this can be done, please refer to the WCAG 2.0 examples for Using a script to scroll content, and providing a mechanism to pause it (link resides outside of ibm.com).
Example 7
Provide a mechanism to allow users to display moving, scrolling, or auto-updating text in a static window or area. An example would be an information box or marquee on ibm.com that scrolled a large block of text. A button lets the user stop the scrolling and display the entire block of text.
For a detailed example of how this can be done, please refer to the WCAG 2.0 examples for Providing a mechanism to allow users to display moving, scrolling, or auto-updating text in a static window or area (link resides outside of ibm.com).
Recommended development techniquess
The techniques above are required; the following techniques are recommended to enhance accessibility. See WCAG 2.0 Additional Techniques (Advisory) for 2.2.1 (link resides outside of ibm.com) for a list of techniques and examples.
Required test techniques
The following test tools and techniques are required to test this checkpoint.
Test tools:
Install the following tools to test this checkpoint:
Required accessibility verification test techniques:
Use the following accessibility verification test (AVT) techniques to validate the Web content. It is recommended that these tests be performed in order.
| Action | Result | |
|---|---|---|
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Test the Web site with a Web syntax analyzer to verify the compliance criteria as follows:
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Pass:
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| Action | Result | |
|---|---|---|
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Verify the compliance criteria for this technique as follows.
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Pass:
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®2009 IBM Corporation
Last updated September 01, 2009.
W3C Recommendation 11 December 2008: http://www.w3.org/TR/WCAG20/ (link resides outside of ibm.com)
Copyright 1994-2009 W3C (Massachusetts Institute of Technology, European Research Consortium for Informatics and Mathematics, Keio University), All Rights Reserved.