1.1 Ensure that users have access to the operating system accessibility tools, without affecting application functionality

Most operating systems include accessibility tools to help users with impairments carry out the basic functions. These may include the following (although the names may differ from one system to another):

  • Sticky Keys - Enables the user to generate combination key presses, such as Ctrl+Alt+F, by pressing the keys one at a time.
  • Toggle Keys - Causes audible and visible alerts to be generated when the Caps Lock, Num Lock or Scroll Lock keys are pressed.
  • Sound Sentry - Ensures that system sounds (beeps) are accompanied by a visible alert, such as a screen flash.
  • Repeat Keys - Enables the user to adjust the rate at which keys repeat when held down.
  • Slow Keys - Enables the user to adjust the length of time keys must be held down before the key press is accepted.
  • Bounce Keys or Filter Keys - Prevents the keyboard from accepting quick consecutive presses of the same key.
  • Mouse Keys - Enables the user to move the mouse pointer using the arrow keys.
  • Screen reader - Reads aloud the screen contents in a synthetic voice.
  • Screen magnifier - Magnifies the area of the screen around the focus point and displays it in a separate window.
  • On-screen keyboard - A software keyboard, displayed on the screen, which emulates the hardware keyboard.

If these tools are provided by the operating system, users should be able to switch them on and off in the normal way. Using them should not block access to any of the application's functionality.

Similar guidelines are:

  • 1.3 Adhere to all user-selected system settings for input and output
  • 1.4 Adhere to the standard keyboard access methods


Many users cannot operate their computer at all without using accessibility features like Sticky Keys that are provided with the operating system. For example, a person who has limited use of only one hand may be physically unable to hold down a modifier key, such as Ctrl, and stretch the distance required to press a letter key at the same time. With Sticky Keys switched on, they can do this, because it eliminates the need to press several keys simultaneously. If an application interferes with Sticky Keys in any way, some functions may become unusable.

Directions and Techniques

Avoid using the accessibility tool enabling actions for application functions

Accessibility tools are often switched on and off by carrying out a specific keyboard action of sequence of actions. For example, on many operating systems, pressing the Shift key 5 times turns on Sticky Keys. In Windows, holding down the right Shift key for 8 seconds turns on Filter Keys. And on the Macintosh, pressing Command-Shift-Clear enables MouseKeys.
Information on Windows accessibility tools.
Information on Mac OS System 7, 8 & 9 accessibility tools.
Information on Mac OS X accessibility tools.
Information on Unix/Linux AccessX accessibility tools.

How you could check for this:

Try switching each of the available accessibility tools on and off, using the keyboard, while the application is running

If you can verify that each tool always works after its keyboard enabling action has been performed, and that it stops working when its disabling action is performed, then you can be sure that the application does not interfere with access to the tools.

Verify that the application functionality is unaffected by use of the accessibility tools

The best way to do this is to arrange for the application to be tested by someone who normally uses the operating system accessibility tools. If it is difficult to find such a person, developers can try using each tool themselves to perform a range of application functions.