Overview
- W3C/WAI Overview
- Accessibility Components
- Introducing WCAG 2.0
W3C/WAI Overview
- » W3C/WAI Overview
- Accessibility Components
- Introducing WCAG 2.0
World Wide Web Consortium, W3C
Leading the Web to Its Full Potential...
- International vendor-neutral industry consortium (currently ~400 Members)
- Evolution and interoperability of the Web:
for everyone, everywhere on every thing
- Operates from: MIT, ERCIM, and Keio
- Develops key Web technologies such as:
HTML, CSS, XML, SVG, SMIL, ...
Web Accessibility Initiative, WAI
Operates under the W3C Process to provide:
- Accessibility support in W3C technologies
- Guidelines for implementing accessibility
- Methods for evaluating accessibility
- Conducting education and outreach
- Coordinating with research and development
Impact of Web Accessibility
Accessibility barriers on the Web potentially exclude a significant population from equal participation, this includes people with:
- Visual, hearing, physical, cognitive, or neurological disabilities (and combinations of these)
- Aging related symptoms and deficiencies
- Temporary or situational limitations
- Social or economical limitations
Benefits of Web Accessibility
Web accessibility has additional benefits:
- Potentially reduces maintenance costs
- Compatible with older computer technologies
- More easily ready for mobile devices
- Available on low bandwidth connections
- Easier to translate to other languages
- Provides support for novice Web users
Accessibility Components
- W3C/WAI Overview
- » Accessibility Components
- Introducing WCAG 2.0
Essential Components
Example of Interaction
When Components Are Weak...
Sometimes other components can compensate through "work-arounds"
- require much more effort
- not good solutions overall
- often not implemented
Introducing WCAG 2.0
- W3C/WAI Overview
- Accessibility Components
- » Introducing WCAG 2.0
Why WCAG 2.0?
- WCAG 1.0 published 5 May 1999
- WCAG 1.0 is HTML and CSS centric
- WCAG 1.0 has assumptions about user agents
- WCAG 1.0 is sometimes ambigous or unclear
- The Web has evolved a lot since 1999
Good news: basic requirements of people with disabilities hardly changed; WCAG 1.0 is still a very good start
WCAG Documents
W3C Rec Track
WCAG 2.0 Structure
- Principle
- Guideline
- Level 1
- Success Criteria
- (Technology-specific techniques)
- Level 2
- Success Criteria
- (Technology-specific techniques)
- Level 3
- Success Criteria
- (Technology-specific techniques)
Example #1
- Principle 1: Content must be perceivable
- Guideline 1.4: Make it easy to distinguish foreground information from its background
- Level 1 Success Criteria for Guideline 1.4
- (No level 1 success criteria for this guideline.)
- Level 2 Success Criteria for Guideline 1.4
- 1.4.1 Text or diagrams, and their background, have a luminosity contrast ratio of at least 5:1.
- 1.4.2 A mechanism is available to turn off background audio that plays automatically, without requiring the user to turn off all audio.
- Level 3 Success Criteria for Guideline 1.4
- 1.4.3 Text or diagrams, and their background, have a luminosity contrast ratio of at least 10:1.
- 1.4.4 Audio content does not contain background sounds, background sounds can be turned off, or background sounds are at least 20 decibels lower than the foreground audio content, with the exception of occasional sound effects.
WCAG 2.0 Conformance
WCAG 2.0 conformance claims inlcude:
- Conformance Level: WCAG 2.0 Level A, AA or AAA
- Baseline: technologies tested (HTML, CSS, etc.)
- Scope: content tested (eg. list of URIs etc.)
- (Optional) user agents used for testing
- ...and many others such as date of the claim etc.
WCAG 2.0 Baselines
Draft: About Baselines and WCAG 2.0
- Set of technologies that an author assumes are supported and turned on in user agents and assistive technologies
- Web content meets WCAG 2.0 at the stated level of conformance if a user agent can support the technologies listed in the baseline
Note: the baseline does not include user agents, but the conformance claim could.
WCAG 2.0 Techniques
Working Draft: Techniques for WCAG 2.0
- Technology-specific techniques for meeting (or failing) success criteria
- Each Technique includes:
- Applicability
- User Agent and Assistive Technology Support Notes
- Description
- Examples
- Resources
- Related Techniques
- Tests
Understanding WCAG 2.0
Working Draft: Understanding WCAG 2.0
- Essential guide to learning and implementing WCAG 2.0
- Each section includes:
- Key terms
- Intent of the success criterion
- Techniques
- Benefits, how it helps people with disabilities
- Examples
- Related resources
WCAG 2.0 Status
- W3C Recommendation Track Documents
- Supporting documents (W3C Note or other)
Example #2
- WCAG 1.0 Checkpoint
- 2.2 Ensure that foreground and background color combinations provide sufficient contrast when viewed by someone having color deficits or when viewed on a black and white screen
- WCAG 2.0 Success Criteria
- 1.4.1 Text or diagrams, and their background, have a luminosity contrast ratio of at least 5:1
- 1.4.3 Text or diagrams, and their background, have a luminosity contrast ratio of at least 10:1
Understanding WCAG 2.0: examples of evaluation tools that implement the luminosity contrast ratio algorithm.
Example #3
- WCAG 1.0 Checkpoint
- 13.1 Clearly identify the target of each link
- WCAG 2.0 Success Criteria
- 2.4.4 Each link is programmatically associated with text from which its purpose can be determined.
- 2.4.8 The purpose of each link can be programmatically determined from the link
Understanding WCAG 2.0: "The intent of this success criterion is to help users understand the purpose of each link in the content, so they can decide whether they want to follow the link [...]"
