Web Site Accessibility
Guidelines for SCS Webmasters

What is Accessibility? - Making Your Web Site Accessible
Checklist for Accessibility
Must Have Items - Should Have Items - Try To Have Items
Items for More Experienced Webmasters
Apply These Items if Your Use These Special Features

Rationale

Displays which flicker or flash can cause photosensitive epileptic seizures in susceptible individuals, particularly if the flash has a high intensity and is within the frequency range between 2 Hz and 55 Hz. This includes flashing text, turning graphics on and off, or repeatedly changing between different images on the screen.

Currently, browsers and assistive technologies do not allow users to control flickering or blinking, so you should avoid causing the screen to flicker or blink.

Techniques for blinking, moving or flickering content

The following techniques may be used to meet Checkpoint 3 from the list of "Must Have" Checkpoints.

The following techniques may be used to meet the checkpoint described in the Special Features - Applets/Scripts #3 section of the Checklist for Web Site Accessibility.

Use style sheets to create movement

By using style sheets with scripting to create movement, you can give the user the ability to turn off the movement by turning off the style sheets.

Recommended techniques to enhance accessibility

The following techniques are recommended to enhance accessibility:

• Minimize the area of the screen which is flashing. Smaller areas are less likely to cause seizures.
• Avoid flashing which has a high level of contrast between the states. Some individuals are more susceptible to high intensity flashing.

Testing

View the page with a browser displaying graphics. Ensure that there is no blinking, flickering, or movement on the page. If any information is conveyed through blinking, flickering, or movement, this will be obvious. Turn off style sheets to verify that the movement can be turned off. If the blinking and flickering do not stop when style sheets are disabled, the page is not accessible.

What is Accessibility? - Making Your Web Site Accessible
Checklist for Accessibility
Must Have Items - Should Have Items - Try To Have Items
Items for More Experienced Webmasters
Apply These Items if Your Use These Special Features