ACTION-258 - Rewrite 4.4.1 to include the user interface and default
presentation of recognized flashing Web content never violate and create
user has the option to...

4.4.1 Below Threshold: The user interface never violates the general flash
or red flash thresholds.

Three Flashes or Below Threshold: The user interface does 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.

NEW #1:
The user agent defined flash rates are less than 3 times in any one second,
for all items for which the user agent has sole control of the rate.<Level

Intent: The intent of this Success Criterion is to guard against inducing
seizures in individuals with photosensitive seizure disorders. There are
HTML elements and CSS value that cause content to flash at an arbitrary
rate. This flashing rate is only controlled the browser. These elements are
not author configurable, nor does the user have any control of the flashing
rate. Potentially harmful flashes occurs when there is a pair of
significantly opposing changes in luminance (general flashing), or a
transition to or from a saturated red occurs irrespective of luminance (red

Examples:  HTML <blink>, CSS - text-decoration property - 'blink' value 

ITC Guidance Note for Licensees on Flashing Images and Regular Patterns in

WCAG20 General Flash and red flash thresholds- 

NEW #2:
4.4.b The user has the option to set flash rates for user agent defined
flash. (Level AAA)

Jim Allan, Accessibility Coordinator & Webmaster
Texas School for the Blind and Visually Impaired
1100 W. 45th St., Austin, Texas 78756
voice 512.206.9315    fax: 512.206.9264
"We shape our tools and thereafter our tools shape us." McLuhan, 1964

Received on Wednesday, 16 December 2009 23:33:18 UTC