function swapImageOff(imgName) {
	if (document.images) {
		document[imgName].src = eval(imgName + "_Off.src");
		document[imgName].src = previous_img;
		previous_img = "";
	}
}

function swapImageOn(imgName) {
	if (document.images) {
		previous_img = document[imgName].src;
		document[imgName].src = eval(imgName + "_On.src");
	}
}