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IBM Web Accessibility Checklist, W3C Web Content Accessibility Guidelines (WCAG) and US Section 508

IBM Web Accessibility Checklist, W3C Web Content Accessibility Guidelines 2.0 (WCAG 2.0) and US Section 508.

There are two major Web standards used today to define accessible Web content for people with disabilities: W3C Web Content Accessibility Guidelines version 2.0 (WCAG 2.0) (link resides outside of ibm.com) and US Section 508 of the Rehabilitation Act of 1973 (link resides outside of ibm.com). (See note 1). WCAG 2.0, developed by a working group in an open consensus process, was published in December 2008. US Section 508, finalized in December 2000, was developed by the US Access Board based on recommendations from a committee composed of academics, disability advocates, and industry representatives. US federal government agencies are required by law to make their Web sites comply with the requirements in Section 508. Many US state governments also have laws or policies that require their Web sites to meet Section 508 requirements. Outside the US, however, most governments with accessibility policies refer to WCAG 2.0 as their accessibility standard.

IBM provides these comparisons of the two standards and IBM's guidelines to help Web site designers navigate these similar, but not identical standards. Table 1 illustrates the IBM, US Section 508, and WCAG 2.0 checkpoints that are functionally equivalent. (See note 2). Table 2 illustrates where the IBM Web Accessibility and US Section 508 checkpoints differ from WCAG 2.0 checkpoints.

Table 1: IBM, Section 508, and WCAG 2.0 equivalent requirements

IBM Web 5.1 Checkpoint

Section 508 Standard

WCAG 2.0

1.1a: Text Alternatives:
All non-text content that is presented to the user has a text alternative that serves the equivalent purpose.

1194.22 (a) A text equivalent for every non-text element shall be provided (e.g., via "alt", "longdesc", or in element content).

1.1.1 Non-text Content: (link resides outside of ibm.com). All non-text content that is presented to the user has a text alternative that serves the equivalent purpose, except for the situations listed below. (Level A)
Controls, Input: All non-text content that is presented to the user has a text alternative that serves the equivalent purpose, except for the situations listed below. (Level A)
Time-Based Media: If non-text content is time-based media, then text alternatives at least provide descriptive identification of the non-text content. (Refer to Guideline 1.2 for additional requirements for media.)
Test: If non-text content is a test or exercise that would be invalid if presented in text, then text alternatives at least provide descriptive identification of the non-text content.
Sensory: If non-text content is primarily intended to create a specific sensory experience, then text alternatives at least provide descriptive identification of the non-text content.
CAPTCHA: If the purpose of non-text content is to confirm that content is being accessed by a person rather than a computer, then text alternatives that identify and describe the purpose of the non-text content are provided, and alternative forms of CAPTCHA using output modes for different types of sensory perception are provided to accommodate different disabilities.
Decoration, Formatting, Invisible: If non-text content is pure decoration, is used only for visual formatting, or is not presented to users, then it is implemented in a way that it can be ignored by assistive technology.

1.1b: Non-text Content
A descriptive label is provided for time-based media, including live audio-only and live video-only content. Non-text content that is used to confirm that content is being accessed by a person rather than a computer is available in different forms to accommodate multiple disabilities.

N/A

1.1.1 Non-text Content: (link resides outside of ibm.com) All non-text content that is presented to the user has a text alternative that serves the equivalent purpose, except for the situations listed below. (Level A)

See 1.1.1 above for complete text of guideline.

1.1c: Image maps:
Client-side image maps are used and alternative text is provided for image map hot spots. Equivalent text links are provided if a server-side image map is used.

1194.22 (e) Redundant text links shall be provided for each active region of a server-side image map.
1194.22 (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.

N/A

1.2a: Captions:
Captions are provided for pre-recorded multimedia.

1194.22 (b) Equivalent alternatives for any multimedia presentation shall be synchronized with the presentation.

1.2.2 Captions (Prerecorded) (link resides outside of ibm.com):. Captions are provided for all prerecorded audio content in synchronized media, except when the media is a media alternative for text and is clearly labeled as such. (Level A)

1.2b: Audio and Video (Prerecorded):
An alternative for time-based media or audio description of the prerecorded video content is provided for synchronized media, except when the media is a media alternative for text and is clearly labeled as such.

1194.22 (b) Equivalent alternatives for any multimedia presentation shall be synchronized with the presentation.

1.2.1 Audio-only and Video-only (Prerecorded) (link resides outside of ibm.com):. For prerecorded audio-only and prerecorded video-only media, the following are true, except when the audio or video is a media alternative for text and is clearly labeled as such: (Level A)
Prerecorded Audio-only: An alternative for time-based media is provided that presents equivalent information for prerecorded audio-only content.
Prerecorded Video-only: Either an alternative for time-based media or an audio track is provided that presents equivalent information for prerecorded video-only content.

1.2c: Live Multimedia:
Captions are provided for live multimedia.

1194.22 (b) Equivalent alternatives for any multimedia presentation shall be synchronized with the presentation.

1.2.4 Captions (Live) (link resides outside of ibm.com): Captions are provided for all live audio content in synchronized media. (Level AA)
Note: This is an AA requirement in WCAG 2.0

1.3a: Information and Relationships: Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text.

N/A

1.3.1 Info and Relationships (link resides outside of ibm.com): Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text. (Level A)

1.3c: Meaningful Sequence When the sequence in which content is presented affects its meaning, a correct reading sequence can be programmatically

N/A

1.3.2 Meaningful Sequence:  (link resides outside of ibm.com) When the sequence in which content is presented affects its meaning, a correct reading sequence can be programmatically determined. (Level A)

1.3d: Forms: Form element labels can be programmatically determined.

1194.22 (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.

1.3.1 Info and Relationships (link resides outside of ibm.com): Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text. (Level A)

1.3e: Tables: Table cells and relationships between cells can be programmatically determined.

1194.22 (g) Row and column headers shall be identified for data tables.
1194.22 (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.

1.3.1 Info and Relationships (link resides outside of ibm.com): Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text. (Level A)

1.3f: Cascading style sheets: Web pages are readable without requiring style sheets.

1194.22 (d) Documents shall be organized so they are readable without requiring an associated style sheet.

1.3.1 Info and Relationships (link resides outside of ibm.com): Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text. (Level A)

1.3g: Sensory Characteristics:
Instructions provided for understanding and operating content do not rely solely on sensory characteristics of components such as shape, size, visual location, orientation, or sound.

N/A

1.3.3 Sensory Characteristics (link resides outside of ibm.com): Instructions provided for understanding and operating content do not rely solely on sensory characteristics of components such as shape, size, visual location, orientation, or sound. (Level A)

1.4a: Use of Color: Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element.

1194.22 (c) Web pages shall be designed so that all information conveyed with color is also available without color, for example from context or markup.

1.4.1 Use of Color (link resides outside of ibm.com): Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element. (Level A)
Note: This success criterion addresses color perception specifically. Other forms of perception are covered in Guideline 1.3 including programmatic access to color and other visual presentation coding.

1.4b: Audio Control: If any audio on a Web page plays automatically for more than 3 seconds, either a mechanism is available to pause or stop the audio, or a mechanism is available to control audio volume independently from the overall system volume level.

N/A

1.4.2 Audio Control (link resides outside of ibm.com): If any audio on a Web page plays automatically for more than 3 seconds, either a mechanism is available to pause or stop the audio, or a mechanism is available to control audio volume independently from the overall system volume level. (Level A)
Note: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether or not it is used to meet other success criteria) must meet this success criterion.

2.1a: Keyboard: All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints.

N/A

2.1.1 Keyboard (link resides outside of ibm.com): All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints. (Level A)
Note: (1)This exception relates to the underlying function, not the input technique. For example, if using handwriting to enter text, the input technique (handwriting) requires path-dependent input but the underlying function (text input) does not. (2)This does not forbid and should not discourage providing mouse input or other input methods in addition to keyboard operation.

2.1b: Scripts: Scripts are keyboard accessible. If the content affected by scripting is not accessible, an alternative is provided.

1194.22 (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 ready by assistive technology.

2.1.1 Keyboard (link resides outside of ibm.com): All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints. (Level A)
Note: (1) This exception relates to the underlying function, not the input technique. For example, if using handwriting to enter text, the input technique (handwriting) requires path-dependent input but the underlying function (text input) does not. (2) This does not forbid and should not discourage providing mouse input or other input methods in addition to keyboard operation.

2.1c: Applets, plug-ins: and non-HTML content. A link is provided to a directly accessible applet, plug-in or other application. Alternate content is provided for those applets, plug-ins or other applications that are not directly accessible.

1194.22 (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).

2.1.1 Keyboard (link resides outside of ibm.com): All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints. (Level A)
Note: (1) This exception relates to the underlying function, not the input technique. For example, if using handwriting to enter text, the input technique (handwriting) requires path-dependent input but the underlying function (text input) does not.(2): This does not forbid and should not discourage providing mouse input or other input methods in addition to keyboard operation.

2.1d: No Keyboard Trap: If keyboard focus can be moved to a component of the page using a keyboard interface, then focus can be moved away from that component using only a keyboard interface, and, if it requires more than unmodified arrow or tab keys, the user is advised of the method for moving focus away.

N/A

2.1.2 No Keyboard Trap (link resides outside of ibm.com):  If keyboard focus can be moved to a component of the page using a keyboard interface, then focus can be moved away from that component using only a keyboard interface, and, if it requires more than unmodified arrow or tab keys or other standard exit methods, the user is advised of the method for moving focus away. (Level A)
Note: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion.

2.2a: Adjust time response:  The user is allowed to turn off, adjust or extend all time limits that are not a real-time, essential or 20 hour exception.

1194.22 (p) When a timed response is required, the user shall be alerted and given sufficient time to indicate more time is required.

2.2.1 Timing Adjustable (link resides outside of ibm.com): For each time limit that is set by the content, at least one of the following is true: (Level A)
Turn off: The user is allowed to turn off the time limit before encountering it; or
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
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; or
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; or
Essential Exception: The time limit is essential and extending it would invalidate the activity; or
20 Hour Exception: The time limit is longer than 20 hours.
Note: This success criterion helps ensure that users can complete tasks without unexpected changes in content or context that are a result of a time limit. This success criterion should be considered in conjunction with Success Criterion 3.2.1, which puts limits on changes of content or context as a result of user action.

2.2b: Pause, Stop, Hide: The user is allowed to pause, stop, or hide moving, blinking, scrolling, or auto-updating information unless it is an essential part of an activity.

N/A

2.2.2 Pause, Stop, Hide (link resides outside of ibm.com): For moving, blinking, scrolling, or auto-updating information, all of the following are true: (Level A)
Moving, blinking, scrolling: For any moving, blinking or scrolling information that (1) starts automatically, (2) lasts more than five seconds, and (3) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it unless the movement, blinking, or scrolling is part of an activity where it is essential; and
Auto-updating: For any auto-updating information that (1) starts automatically and (2) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it or to control the frequency of the update unless the auto-updating is part of an activity where it is essential.
Note: (1) For requirements related to flickering or flashing content, refer to Guideline 2.3. (2) Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference. (3) Content that is updated periodically by software or that is streamed to the user agent is not required to preserve or present information that is generated or received between the initiation of the pause and resuming presentation, as this may not be technically possible, and in many situations could be misleading to do so. (4) An animation that occurs as part of a preload phase or similar situation can be considered essential if interaction cannot occur during that phase for all users and if not indicating progress could confuse users or cause them to think that content was frozen or broken.

2.3a: Flashing Content or Below Threshold: Web pages do not contain anything that flashes more than three times in any one second period, or the flash is below the general flash and red flash thresholds.

1194.22 (j) Pages shall be designed to avoid causing the screen to flicker with a frequency greater than 2Hz and lower than 55 Hz.

2.3.1 Three Flashes or Below Threshold (link resides outside of ibm.com): Web pages do not contain anything that flashes more than three times in any one second period, or the flash is below the general flash and red flash thresholds. (Level A)
Note: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion.

2.4a: Navigational features: A mechanism is available to bypass blocks of content that are repeated on multiple Web pages.

1194.22 (o)A method shall be provided that permits users to skip repetitive navigation links

2.4.1 Bypass Blocks (link resides outside of ibm.com):  A mechanism is available to bypass blocks of content that are repeated on multiple Web pages. (Level A)

2.4b: Skip to main content:
Note: This checkpoint was removed from the 5.1 version of the Web checklist.  If you comply with checkpoint 2.4a, you will also comply with the former 2.4b checkpoint.

 

 

2.4c: Frames: A title and an accessible frame source are provided for each frame.

1194.22 (i) Frames shall be titled with text that facilitates frame identification and navigation.

2.4.1 Bypass Blocks (link resides outside of ibm.com): A mechanism is available to bypass blocks of content that are repeated on multiple Web pages. (Level A)

2.4d: Page Titles and Link Purpose: Web pages have titles that describe topic or purpose.

N/A

2.4.2 Page Titled (link resides outside of ibm.com): Web pages have titles that describe topic or purpose. (Level A)

2.4e: Focus Order: If a Web page can be navigated sequentially and the navigation sequences affect meaning or operation, focusable components receive focus in an order that preserves meaning and operability.

N/A

2.4.3 Focus Order (link resides outside of ibm.com): If a Web page can be navigated sequentially and the navigation sequences affect meaning or operation, focusable components receive focus in an order that preserves meaning and operability. (Level A)

2.4f: Link PurposeThe purpose of each link can be determined from the link text alone or from the link text together with its programmatically determined link context, except where the purpose of the link would be ambiguous to users in general.

N/A

2.4.4 Link Purpose (In Context) (link resides outside of ibm.com):
The purpose of each link can be determined from the link text alone, or from the link text together with its programmatically determined link context, except where the purpose of the link would be ambiguous to users in general.

3.1a: Language of Page: The default human language of each Web page can be programmatically determined.

N/A

3.1.1 Language of Page (link resides outside of ibm.com): The default human language of each Web page can be programmatically determined. (Level A)

3.2a: On Focus: When any component receives focus, it does not initiate a change of context.

N/A

3.2.1 On Focus (link resides outside of ibm.com): When any component receives focus, it does not initiate a change of context. (Level A)

3.2b: On Input: Changing the setting of any user interface component does not automatically cause a change of context unless the user has been advised of the behavior before using the component.

N/A

3.2.2 On Input (link resides outside of ibm.com): Changing the setting of any user interface component does not automatically cause a change of context unless the user has been advised of the behavior before using the component. (Level A)

3.3a: Error Identification: If an input error is automatically detected, the item that is in error is identified and the error is described to the user in text.

N/A

3.3.1 Error Identification (link resides outside of ibm.com): If an input error is automatically detected, the item that is in error is identified and the error is described to the user in text. (Level A)

3.3b: Labels or Instructions: Labels or instructions are provided when content requires user input. For all user interface components, the name and role can be programmatically determined, values that can be set by the user can be programmatically set, and notification of changes to these items is available to user agents, including assistive technologies.

N/A

3.3.2 Labels or Instructions (link resides outside of ibm.com): Labels or instructions are provided when content requires user input. (Level A)

4.1a: Parsing: In content implemented using markup languages, elements have complete start and end tags, elements are nested according to their specifications, elements do not contain duplicate attributes, and any IDs are unique, except where the specifications allow these features.

N/A

4.1.1 Parsing (link resides outside of ibm.com): In content implemented using markup languages, elements have complete start and end tags, elements are nested according to their specifications, elements do not contain duplicate attributes, and any IDs are unique, except where the specifications allow these features. (Level A) Note: Start and end tags that are missing a critical character in their formation, such as a closing angle bracket or a mismatched attribute value quotation mark are not complete.

4.1b: Name, Role, Value: For all user interface components (including but not limited to: form elements, links and components generated by scripts), the name and role can be programmatically determined; states, properties, and values that can be set by the user can be programmatically set; and notification of changes to these items is available to user agents, including assistive technologies.

N/A

4.1.2 Name, Role, Value (link resides outside of ibm.com): For all user interface components (including but not limited to: form elements, links and components generated by scripts), the name and role can be programmatically determined; states, properties, and values that can be set by the user can be programmatically set; and notification of changes to these items is available to user agents, including assistive technologies. (Level A)
Note: This success criterion is primarily for Web authors who develop or script their own user interface components. For example, standard HTML controls already meet this success criterion when used according to specification.

4.2a: Text-only page: If accessibility cannot be accomplished in any other way, a text-only page with equivalent information or functionality is provided.

1194.22 (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.

N/A

4.2b: Accessibility-Supported Technologies Only: Use accessibility supported technologies. Any information or functionality that is implemented in technologies that are not accessibility supported must also be available via technologies that are accessibility supported.

N/A

All WCAG 2.0 Success Criteria are written as testable criteria for objectively determining if content satisfies them. Testing the Success Criteria would involve a combination of automated testing and human evaluation. The content should be tested by those who understand how people with different types of disabilities use the Web. Understanding Conformance (link resides outside of ibm.com).


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.

®2010 IBM Corporation

Last updated March 1, 2010.



1Detailed in 36 Code of Federal Regulations Section 1194.22 Web-based intranet and internet information and applications in the US Section 508 Technical Standards (link resides outside of ibm.com).

2 See the Note to §1194.22 located after §1194.22 (p) in the US Section 508 Technical Standards (link resides outside of ibm.com).