Error COBCH1728 ("type-name1 does not have public implementation of method method-name of interface type-name2") is also produced with this error.
In the following example, this error is returned for System.Windows.Forms.Control:
$set ilref"System.Windows.Forms"
class-id MainView
inherits type System.Windows.Forms.Form
implements type IMainView.
end class.
interface-id IMainView public.
method-id Show.
end method.
end interface.