if (document.images) {
a1_off = new Image(); a1_off.src = "images/but_rest.jpg"
a1_over = new Image(); a1_over.src = "images/but_rest_over.jpg"
a2_off = new Image(); a2_off.src = "images/but_taxi.jpg"
a2_over = new Image(); a2_over.src = "images/but_taxi_over.jpg"
}

function turn_off(ImageName) {
	if (document.images != null) {
		document[ImageName].src = eval(ImageName + "_off.src");
	}
}

function turn_over(ImageName) {
	if (document.images != null) {
		document[ImageName].src = eval(ImageName + "_over.src");
	}
}