Web Accessibility Coordination (WAC)

Graphics, Multimedia and Dynamic Content

Non-text materials cannot be read by screen readers and text-only browsers. Provide text alternatives.

Use the ALT attribute to provide text equivalents for all IMG elements
Provide text equivalents for all other non-text items
Provide equivalent alternatives for any multimedia presentation and synchronize these alternatives with the presentation
People with photosensitive epilepsy can have seizures triggered by flickering or flashing in the 4 to 59 flashes per second (Hertz) range with a peak sensitivity at 20 flashes per second as well as quick changes from dark to light (like strobe lights). If you include animated gif images or other refreshing content that cause the screen to flicker, avoid causing a flicker with a frequency greater than 2 Hertz and lower than 55 Hertz.
Until user agents provide the ability to stop the refresh, do not create periodically auto-refreshing pages.
When an appropriate markup language exists, use markup rather than images to convey information. For example, MathML, CML
Until user agents provide the ability to stop auto-redirect, do not use markup to redirect pages automatically. Instead, configure the server to perform redirect