function showLayer(layerName) {
	if (document.getElementById) {
		var targetElement = document.getElementById(layerName);
		targetElement.style.display = 'block';
	}
}
function hideLayer(layerName) {
	if (document.getElementById) {
		var targetElement = document.getElementById(layerName);
		targetElement.style.display = 'none';
	}
}
function bgOn(layerName) {
	if (document.getElementById) {
		var targetElement = document.getElementById(layerName);
		targetElement.style.background = 'url(/images/toplinkon.gif)';
	}
}
function bgOff(layerName) {
	if (document.getElementById) {
		var targetElement = document.getElementById(layerName);
		targetElement.style.background = 'none';
	}
}