<br />AChecker is used to check the accessibility of course content. It requires a new access key from <a href="https://achecker.ca" target="acheck">achecker.ca</a> to enable it. Create an account there if you don't have one, then copy the Web Service ID from your <a href="https://achecker.ca/profile/index.php" target="acheck">achecker.ca Profile page</a>, to the AChecker Key field in ATutor System Preferences.