Techniques for WCAG 2.0

When content that is rendered by a plug-in or contained in an applet blinks, there may be no way for the user agent to pause the blinking. If neither the plug-in, applet, nor the content itself provides a mechanism to pause the content, the user may not have sufficient time to read the content between blinks or it may be so distracting that the user will not be able to read other content on the page.

• Using scripts to control blinking and stop it in three seconds or less

Procedure

For each page that has blinking content in a plugin or applet:

1. Determine if the content continues to blink for longer than 3 seconds.

2. Determine if there is a means to pause the blinking content.

Expected Results

• If step #1 is true and step #2 is false, the content fails the success criterion.

This describes a failure condition for all techniques involving captions. If the "caption" does not include all of the dialog (either verbatim or in essence) as well as all important sounds then the 'Captions' are not real captions.

NOTE: Captions sometimes simplify the spoken text both to make it easier to read and to avoid forcing the viewer to read at very high speed. This is standard procedure and does not invalidate a caption.

No resources available for this technique.

(none currently listed)

Procedure

1. View the material with captioning turned on.

2. Check that all dialog is accompanied by a caption.

3. Check that all important sounds are captioned.

Expected Results

• Step #2 and step #3 are true.

This document describes a failure that occurs when removing focus from a form element, such as by moving to the next element, causes a change of context.

• Failure of SC 3.2.5 due to launching a new window when a user enters text into an input field
• Failure of SC 3.2.2 due to launching a new window without prior warning when the status of a radio button, check box or select list is changed

Procedure

1. Find all form elements.

2. Go through them in order.

3. Check if the form submits when you move from one field to the next.

4. Check if moving from one field to the next launches any new windows.

5. Check if moving from one filed to the next navigates to another screen.

Expected Results

• If step #3, step #4, or step #5 is true, then this failure condition applies and the content fails the success criterion.

When content includes multiple formats, one or more user agents or plug-ins are often needed in order to successfully present the content to users. For example, a page that includes (X)HTML, SVG, SMIL and XForms may require a browser to load as many as three different plug-ins in order for a user to successfully interact with the content. Some plug-ins create a common situation in which the keyboard focus can become "stuck" in inaccessible plug-ins, leaving a keyboard-only user with no way to return to the accessible content.

No resources available for this technique.

• Using both keyboard and other device-specific functions
• Ensuring that users are not trapped in content

Procedure

1. Using a keyboard, navigate through the content.

2. Check to see that the keyboard focus is not "trapped" and it is possible to move keyboard focus out of the plug-in content without closing the user agent or restarting the system.

Expected Results

• If the keyboard focus becomes "trapped," then this failure condition applies and content fails the success criterion.

Web servers that require user authentication usually have a session mechanism in which a session times out after a period of inactivity from the user. This is sometimes done for security reasons, to protect users who are assumed to have left their computer exposed in a state where someone could do something harmful to them such as transfer bank funds or make an unauthorized purchase. A user with a disability may actually still be working to complete the form as it may take him or her longer to complete the form than would normally be expected. Upon re-authentication, if the state of the user's session is not restored, including all data that had been previously entered into the form, he or she will have to start over. And for these users, it is likely that the session will time out again before they can complete the form. This sets up a situation where a user who needs more time to complete the form can never complete it.

• Saving data so that it can be used after a user re-authenticates

Procedure

On a site where authentication is required, user input is collected, and which ends the user's session after a known period of inactivity:

1. Provide user input as required but allow the session to time out, then submit the form.

2. When requested, re-authenticate with the server.

3. Determine if the function is performed using the previously submitted data.

Expected Results

• If step #3 is false, the site fails the success criterion.

This objective of this technique is to describe the failure that occurs when an image uses color to convey information, but the text alternative for the image does not convey that information. This can cause problems for people who are blind or colorblind because they will not be able to perceive the information conveyed by the color.

No resources available for this technique.

• Providing short text alternative for non-text content that serves the same purpose and presents the same information as the non-text content

Procedure

For all images in the content that convey information by way of color :

1. Check that the information conveyed by color is not included in the text alternative for the image.

Expected Results

• If step #1 is true, then this failure condition applies and content fails the success criterion.

The objective of this technique is to show how identifying content only by its shape or location makes content difficult to understand and operate. When only visual identification or location is used, users with visual disabilities may find it difficult to locate content since they cannot see the screen or may perceive only a small portion of the screen at one time. Also, location of content can vary if page layout varies due to variations in font, window, or screen size.

No resources available for this technique.

• Providing textual identification of items that otherwise rely only on shape and/or position to be understood

Procedure

1. Examine the Web unit for textual references to content within the Web unit.

2. Check that the references do not rely on only the shape or location of the content.

Expected Results

• If step #2 is false, then this failure condition applies and the content fails this success criterion.

When standard controls from accessible technologies are used, they usually are programmed in a way that uses and supports the accessibility API. If custom controls are created, however, then it is up to the programmer to be sure that the newly created control supports the accessibility API. If this is not done, then assistive technologies will not be able to understand what the control is or how to operate it or may not even know of its existence.

• Active Accessibility Checker (AccExplorer)

• JAVA Accessibility Helper

(none currently listed)

Procedure

1. Using the accessibility checker for the technology (or if that is not available, inspect the code or test with an assistive technology), check the controls to see if they support the accessibility API.

Expected Results

• If step #1 is false, then this failure condition applies and the content fails this success criterion

In this failure technique, there is moving or scrolling content that cannot be paused and resumed by users. In this case, some users with low vision or cognitive disabilities will not be able to perceive the content.

• Allowing the content to be paused and restarted from where it was stopped

Procedure

On a page with moving or scrolling content,

1. Check that a mechanism is provided in the Web unit or user agent to pause moving or scrolling content.

2. Use the pause mechanism to pause the moving or scrolling content.

3. Check that the moving or scrolling has stopped and does not restart by itself.

4. Check that a mechanism is provided in the Web unit or user agent to restart the paused content.

5. Use the restart mechanism provided to restart the moving content.

6. Check that the movement or scrolling has resumed from the point where it was stopped.

Expected Results

• If steps step #1, step #3, step #4, or step #6 are false, then the content fails the success criterion.

The objective of this technique is to ensure that Web pages can be interpreted consistently by user agents, including assistive technology. If it is ambiguous, different user agents including assistive technologies could present different information to their users. Users of assistive technology for example may have different information presented to them than users of other mainstream user agents. Some elements and attributes in markup languages are required to have unique values, and if this requirement is not honored, the result can be irregular or not uniquely resolvable content. For example, when id attribute values are not unique, they are particularly problematic when referenced by labels, headers in data tables, or used as fragment identifiers, as user agents do not have enough information to provide determine essential relationships (i.e. to determine which label goes with which item).

No resources available for this technique.

(none currently listed)

Procedure

1. Check for id and accesskey values which are not unique within the document.

2. Check that attribute values that have an idref value have a corresponding id value.

3. For tables that use the axis attribute, check that all values listed in the axis attribute have a corresponding id value in a table header cell in the same table.

4. For client-side image maps, check that the value of the usemap attribute has a corresponding id value if the usemap attribute is not a URL.

Expected Results

• If step #1, step #3 or step #4 is true or step #2 is false, then this failure condition applies and the content fails the success criterion.

This failure technique describes the situation in which an alternate, conforming version of the content is provided, but there is no direct way for a user to tell that it is available or where to find it. Such content fails the success criterion because the user cannot find the conforming version.

• Providing a link at the beginning of the nonconforming content that points to an alternate version that does meet WCAG 2.0 Level 1 success criteria

Procedure

1. Identify a nonconforming page that has an alternative conforming version.

2. Determine if the nonconforming page provides a link to the conforming version.

Expected Results

1. If step #2 is false, the content fails the success criterion.

The objective of this failure condition is to address situations where the non-text content is updated, but the text alternative is not updated at the same time. If the text in the text alternative can not still be used in place of the non-text content without losing information or function, then it fails because it is no longer a text alternative for the non-text content.

No resources available for this technique.

(none currently listed)

Procedure

1. Check each text alternative to see if it is describing content other than the currently-displayed non-text content.

Expected Results

• If step #1 is true then the text alternative is not up to date with current item, this failure condition applies, and content fails the success criterion.

Failure due to opening new windows when the user does not expect them. New windows take the focus away from what the user is reading or doing. This is fine when the user has interacted with a piece of User Interface and expects to get a new window, such as an options dialog. The failure comes when pop-ups appear unexpectedly.

No resources available for this technique.

• Using script to open a new window

Procedure

1. Load the Web unit.

2. Check if new (additional) windows open.

3. Find every actionable element, such as links and buttons, in the Web unit.

4. Activate each element.

5. Check if activating the element opens a new window.

6. Check if elements that open new windows have associated text saying that will happen. The text can be displayed in the link, or available through a hidden association such as an HTML title attribute.

Expected Results

• If step #2 is true, the failure condition applies and the content fails the success criterion

• If step #5 is true and step #6 is false, the failure condition applies and the content fails the success criterion

This describes a failure condition for SC involving sound. If sound does not turn off automatically within 3 seconds and there is no way to turn the sound off then SC 1.4.2 would not be met. Sounds that play over 3 seconds when there is no mechanism to turn off the sound included in the content would fall within this failure condition.

No resources available for this technique.

(none currently listed)

Procedure

1. Check that there is a way in content to turn off any sound that plays more than three seconds.

Expected Results

• If step #1 is not true then content fails Success Criterion 1.4.2

Users with vision loss or cognitive challenges often require specific foreground and background color combinations. For instance, many people with low vision find it much easier to see a Web page that has white text on a black background, so they may have set their user agent to create this contrast. If the author specifies that the text must be black, then it may override the settings of the user agent and render a page that has black text (specified by the author) on black background (that was set in the user agent). This principle also works in reverse. If the Webmaster forces the background to be white, then the white background specified by the author would be the same color as the white text (which was set in the user agent) rendering the page unusable to the user. Therefore, if the author specifies a foreground text color then they should also specify a background color which has sufficient contrast (link) with the foreground and vice versa.

   
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
  <html xmlns="<url>http://www.w3.org/1999/xhtml">http://www.w3.org/1999/xhtml</title>">
      <html>
          <head>
              <title>A study of population dynamics</title>
          </head>
          <body bgcolor="white">
              <p> ... document body...</p>
          </body>
  </html>

  <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<html>
<head>
 <title>Setting the canvas background</title>
    <style type="text/css">

       body {background-color:white}
    </style>
  </head>
  <body>
    <p>My background is white.</p>
  </body>
</html>

 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<html>
<head>
 <title>A study of population dynamics</title>

</head>
<body color="white">
  <p>... document body...</p>
</body>
</html>