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

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