function toggleLayer(layerName)
{
    if (document.getElementById) // Netscape 6 and IE 5+
    {
	var targetElement = document.getElementById(layerName);
	if (targetElement.style.visibility == 'visible')
	{
	    targetElement.style.visibility = 'hidden';
	    targetElement.style.position = 'absolute';
	}
	else
	{
	    targetElement.style.visibility = 'visible';
	    targetElement.style.position = 'relative';
	}
    }
}