function showlayer(layername)
{
    if(document.all){
	document.all[layername].style.visibility="visible";
    }
    else if(document.getElementById){
	document.getElementById(layername).style.visibility="visible";
    }
    else if(document.layers) {
	return document.layers[layername].visibility="visible"; 
    }
}

function hidelayer(layername)
{
    if(document.all){
	document.all[layername].style.visibility="hidden";
    }
    else if(document.getElementById){
	document.getElementById(layername).style.visibility="hidden";
    }
    else if(document.layers) {
	return document.layers[layername].visibility="hidden"; 
    }
}