Navigator 2.0, Internet Explorer 3.0
checked is a read/write Boolean property of the Radio object. If the Radio button is checked, then the checked property is true. If the Radio is not checked, then checked is false.
If you set checked to true, then the Radio button will become selected, and whichever button was previously selected will become deselected. Note, however, that setting the checked property of a radio button to false will have no effect, because at least one button must always be selected, and you cannot deselect a radio button except by selecting some other button.
Note that setting the checked property does not cause the Radio's onClick event handler to be invoked. If you want to invoke that event handler, you must do so explicitly.