'96 Windstar airbag light

My parents '96 Windstar with just over 200K miles had the air bag light come on. I've heard that they come on automatically around 200K miles to remind people to have the air bags checked, and that it just requires taking it to the dealer for the light to be reset. Does anyone know if this is true? If so, is there any way of resetting it yourself, without taking it to a dealer?