function showLayer(layerName) {
	if (document.layers) {
		document.layers[layerName].visibility = "visible";
	}
	else if (document.all) {
		document.all[layerName].style.visibility = "visible";
	}
	else if (document.getElementById) {
		document.getElementById(layerName).style.visibility = "visible";
	}
}

function hideLayer(layerName) {
	if (document.layers) {
		document.layers[layerName].visibility = "hidden";
	}
	else if (document.all) {
		document.all[layerName].style.visibility = "hidden";
	}
	else if (document.getElementById) {
		document.getElementById(layerName).style.visibility = "hidden";
	}
}