All components of a control, excluding the type and handle, are "properties." Control properties are classified into two groups: common properties (those that apply to all types of controls) and special properties (those that are specific to a single type of control). Note, however, that some common properties have a special meaning (or no meaning) for some control types. In addition, some special properties are used by more than one control type. For example, the special properties that apply to bitmap buttons are used also by push button, radio button, and check box controls.