function swap(imgName){
	//alert(imgName);
	imgOn = "images/" + imgName + "_on" + ".gif";
	//alert(imgOn);
	document [imgName].src = imgOn;
}

function swapback(imgName){
	imgOff = "images/" + imgName + "_off" + ".gif";
	document [imgName].src = imgOff;
}