Win32 uses the Accessibility support for controls that are recognized as generic controls. When Win32 locates a control, it tries to get the accessible object along with all accessible children of the control.
Objects returned by Accessibility are either of the class AccessibleControl, Button or CheckBox. Button and Checkbox are treated specifically because they support the normal set of methods and properties defined for those classes. For all generic objects returned by Accessibility the class is AccessibleControl.