Background

§1194.21(e) of Section 508 states that:

“When bitmap images are used to identify controls, status indicators, or other programmatic elements, the meaning assigned to those images shall be consistent throughout an application's performance.”

Software should not change the meaning of an image that is used by a program to identify programmatic features (e.g., bitmap controls) during the operation of a program. Changing the meaning and behavior of an image during the operation of a program is effectively modifying the interface dynamically, which can be confusing to people with cognitive disabilities and other users that memorize the organization of the interface. In addition, changing the behavior of images dynamically may confuse a screen reader, meaning that it may not identify that the change has occurred, thus continuing to report the prior text and behavior.

Images that do not identify programmatic behavior are not applicable (for example, maps that are dynamically painted based on the selected location). Images are sometimes used without text to represent concepts within an application. Most screen readers allow users to assign text names to these images. If the meaning of the image should change during the running of an application, the assigned identifier may no longer be valid and may be confusing to the user. An example is an icon that looks like a floppy disk and is used to represent “SAVE” wherever the icon appears. An icon using the same image with a different meaning will be confusing to the user.

Select the Next button to find out how to assess whether your application conforms to this provision.