function imgSwap(oImg) {
	var strOver = "_on";
	var strOff = "_off";
	var strImg = oImg.src;
	if (strImg.indexOf(strOver) != -1) {
		oImg.src = strImg.replace(strOver, strOff);
	} else {
		oImg.src = strImg.replace(strOff, strOver);
	}
}