Transcript MDDA_WCAG2.0_24.03.2..

All
change
for
WCAG
2.0
WHAT YOU NEED TO KNOW ABOUT THE NEW ACCESSIBILITY
GUIDELINES
Patrick H. Lauke / Manchester Digital Development Agency / 24 March 2009
About me...
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Web Editor for University of Salford
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Web Standards Project (WaSP)
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Author and occasional .net magazine
contributor
NOT an expert?
Outline
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Background on WCAG 1.0
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The painful birth of WCAG 2.0
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Overview of the new guidelines
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Next steps for WCAG 1.0 veterans
Web Content Accessibility Guidelines 1.0
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www.w3.org/TR/WCAG10
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W3C recommendation 5 May 1999
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14 guidelines
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75 checkpoints
WCAG 1.0 – problems
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HTML-centric checkpoints, despite
separate techniques document
http://www.w3.org/TR/WAI-WEBCONTENTTECHS/
“until user agents” clauses
Forbids JavaScript and any non-W3C
technologies
Vague checkpoints
WCAG 2.0 – early attempts
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Work began soon after release of WCAG
1.0
Many iterations, largely under radar of web
devs
Original “Last Call” April 2006
To Hell with WCAG 2.0
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Joe Clark's vitriolic style
A List Apart, 23 May 2006
http://www.alistapart.com/articles/tohellwith
wcag2
Main points of concern:
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Overall size of combined guidelines
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Inscrutable language
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Baseline concept
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Omission of markup validation /
standards
To Hell with WCAG 2.0
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Generated huge interest from web devs
Joe Clark started WCAG Samurai project
to create errata for WCAG 1.0
W3C demoted WCAG 2.0 from Last Call
back to Public Working Draft
WCAG 2.0 back on track
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Joe Clark's leaving speech at @media2007
– confident that WCAG 2.0 heading in
right direction
Historical aside: my take on amended
WCAG 2.0 http://www.webstandards.org/2007/06/11/reviewwcag2-may2007-working-draft/
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Nonetheless released WCAG Samurai
Errata http://wcagsamurai.org/
Web Content Accessibility Guidelines 2.0
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www.w3.org/TR/WCAG20
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W3C recommendation 11 December 2008
WCAG 2.0 suite of documents
WCAG 2.0 suite of documents
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Web Content Accessibility Guidelines 2.0
[normative]
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How to Meet WCAG 2.0 [informative]
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Understanding WCAG 2.0 [informative]
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Techniques for WCAG 2.0 [informative]
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http://www.w3.org/WAI/intro/wcag20
Web Content Accessibility Guidelines 2.0
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4 general principles
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12 guidelines
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61 success criteria
WCAG 2.0 principles
A website should be...
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Perceivable
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Operable
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Usable
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Robust
WCAG 2.0 improvements
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Principles, guidelines and success criteria
are technology-agnostic
WCAG 1.0 examples
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“Guideline 5. Create tables that transform
gracefully”
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“5.3 Do not use tables for layout
unless the table makes sense when
linearized.”
“Note. Once user agents support style sheet
positioning, tables should not be used for layout.”
So what happens with CSS positioning that
breaks linear flow?
WCAG 2.0 examples
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“Guideline 1.3 Adaptable: Create content that can be
presented in different ways (for example simpler layout)
without losing information or structure.”
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“1.3.2 Meaningful Sequence: When the sequence
in which content is presented affects its
meaning, a correct reading sequence can be
programmatically determined.”
WCAG 2.0 improvements
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WCAG 1.0 “Guideline 11. Use W3C
technologies and guidelines”
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“Where it is not possible to use a W3C technology,
or doing so results in material that does not
transform gracefully, provide an alternative version
of the content that is accessible.”
WCAG 2.0 can be applied to W3C and
non-W3C technologies (as long as they're
accessibility-supported)
WCAG 2.0 improvements
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Accessibility-supported technologies
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supported by users' assistive
technology
technology must have accessibilitysupported user agents that are
available to users
WCAG 2.0 accessibility-supported
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You can use PDF, Flash, even JavaScript
JavaScript and WAI-ARIA
http://www.w3.org/TR/wai-aria/
Even if a technology isn't fully accessibilitysupported, as long as you use the
supported bits
Worst case provide fallback that is
supported
WCAG 2.0 improvements
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Removes all “until user agents...” clauses
WCAG 1.0 example
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“Guideline 10. Use interim solutions.”
“10.4 Until user agents handle empty controls correctly,
include default, place-holding characters in edit boxes and
text areas.”
WCAG 2.0 improvements
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Each success criterion is more easily
testable
Success criteria give clearer guidance
than WCAG 1.0 checkpoints
WCAG 1.0 example
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“Guideline 2. Don't rely on color alone.”
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“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.”
What exactly is “sufficient”?
WCAG 2.0 example
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“Guideline 1.4 Distinguishable: Make it easier for users to
see and hear content including separating foreground
from background.”
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AA “1.4.3 Contrast (Minimum): The visual
presentation of text and images of text has a
contrast ratio of at least 4.5:1”
“Large Text: Large-scale text and images of largescale text have a contrast ratio of at least 3:1”
AAA “1.4.6 Contrast (Enhanced): The visual
presentation of text and images of text has a
contrast ratio of at least 7:1”
“Large Text: Large-scale text and images of largescale text have a contrast ratio of at least 4.5:1”
WCAG 2.0 improvements
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As a result of clearer, testable SCs some
things are allowed that previously weren't
WCAG 1.0 example
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“Guideline 7. Ensure user control of timesensitive content changes.”
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“7.1 Until user agents allow users to control
flickering, avoid causing the screen to flicker.”
“7.2 Until user agents allow users to control
blinking, avoid causing content to blink[...]”
WCAG 2.0 example
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“Guideline 2.3 Seizures: Do not design
content in a way that is known to cause
seizures”
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“2.3.1 Three Flashes 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.”
WCAG 2.0 improvements
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Success criteria focus on the outcomes,
not how they're achieved
WCAG 1.0 example
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“Guideline 9. Design for deviceindependence.”
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“9.5 Provide keyboard shortcuts to important
links (including those in client-side image maps),
form controls, and groups of form controls.”
“For example, in HTML, specify shortcuts via the
"accesskey" attribute.”
WCAG 2.0 example
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“Guideline 2.1 Keyboard Accessible: Make
all functionality available from a
keyboard.“
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“2.1.1 Keyboard: All functionality of the content is
operable through a keyboard interface [...]”
WCAG 2.0 improvements
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Talks about mechanisms
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“process or technique for achieving a result”
WCAG 2.0 mechanism example
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“Guideline 2.4 Navigable: Provide ways to help users
navigate, find content, and determine where they are.”
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“2.4.1 Bypass Blocks: A mechanism is available
to bypass blocks of content that are repeated on
multiple Web pages.”
Does this mandate skip links?
WCAG 2.0 mechanism example
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Looking at “How to meet WCAG 2.0”, skip
links only one of a few techniques
mentioned
Sufficient Techniques for 2.4.1 - Bypass Blocks:
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Creating links to skip blocks of repeated material
Grouping blocks of repeated material in a way
that can be skipped
Advisory Techniques for 2.4.1 - Bypass Blocks
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[…]
C6: Positioning content based on structural
markup
WCAG 2.0 techniques
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Techniques cover general technologies:
HTML, CSS, JavaScript, WAI-ARIA
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Sufficient and advisory techniques
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Techniques are informative, not normative
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List of techniques is not exhaustive –
invent your own as long as success
criteria are fulfilled
WCAG 2.0 conformance
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WCAG 1.0 had duality of priority 1,2,3 that
mapped to levels A, AA, AAA
WCAG 2.0 just uses A, AA, AAA model for
both SCs and conformance levels
WCAG 2.0 conformance
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Applies to full pages
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Complete processes
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Only accessibility-supported techs are
relied on
Non-interference (when adding nonaccessibility-supported technologies)
You can conform without a conformance
claim
WCAG 2.0 partial conformance
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3rd party content (UGC, feeds, etc)
Use of languages/technologies without
accessibility-support (future-proofing?)
Transition from WCAG 1.0 to WCAG 2.0
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Needs of users with disabilities hasn't
changed
Technology that they use has
If your site accessible under WCAG 1.0,
shouldn't be too far off WCAG 2.0
Transition from WCAG 1.0 to WCAG 2.0
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How WCAG 1.0 differs from WCAG 2.0
http://www.w3.org/WAI/WCAG20/from10/diff.php
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Comparison WCAG 1.0 checkpoints to
WCAG 2.0
http://www.w3.org/WAI/WCAG20/from10/comparison/
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How to update your site from WCAG 1.0 to
2.0
http://www.w3.org/WAI/WCAG20/from10/websites.html
Transition from WCAG 1.0 to WCAG 2.0
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Evaluate your site based on WCAG 2.0
SCs
Many 1.0 checkpoints map to 2.0 SCs
Are there 1.0 requirements that have been
lifted?
Test more specific 2.0 SCs
Getting started with WCAG 2.0
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WebAIM's unofficial checklist
http://webaim.org/standards/wcag/checklist
Getting started with WCAG 2.0
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For a “one-stop shop” overview,
customisable WCAG 2.0 quick reference
http://www.w3.org/WAI/WCAG20/quickref/
Recap on WCAG 2.0
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Technology-agnostic – applicable to more
present and future technologies
Clearly testable Success Criteria
Focussed on outcome for users, not
techniques
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Removes outdated requirements from 1.0
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Overall allows authors more freedom
Thanks
Patrick H. Lauke
http://www.splintered.co.uk