function toggleLayer(whichLayer) {
	if (document.getElementById) {
		//standard scripting
		var layerStyle = document.getElementById(whichLayer).style;
		layerStyle.display = layerStyle.display? "":"block";
	}
	else if (document.all) {
		//old MSIE
		var layerStyle = document.all[whichLayer].style;
		layerStyle.display = layerStyle.display? "":"block";
	}
	else if (document.layers) {
		//nn4
		var layerStyle = document.layers[whichLayer].style;
		layerStyle.display = layerStyle.display? "":"block";
	}
}