function showLayer(layerName)
{
	if(document.all) // IE
	{
		document.all[layerName].style.visibility = 'visible';
	}
	else if(document.layers) // NS
	{
 		document.layers[layerName].visibility = 'visible';
	}
	else // DOM
	{
		document.getElementById(layerName).style.visibility = 'visible';
	}
}

function hideLayer(layerName)
{
	if(document.all) // IE
	{
		document.all[layerName].style.visibility = 'hidden';
	}
	else if(document.layers) // NS
	{
		document.layers[layerName].visibility = 'hidden';
	}
	else // DOM
	{
		document.getElementById(layerName).style.visibility = 'hidden';
	}
}