nn5 = nn = ie = false; 
if(document.all){//ie
	ie=true;
}else if(document.layers){//nn4
	nn5=true;
}else if(document.getElementById){//6up
	nn=true;
}

function setObj(n){
	var o;
	if(nn5){
		o = document.layers[n];
	}else if(ie){
		o = document.all[n];
	}else{
		o = document.getElementById(n);
	}
	return o;
}

function layerOn(n){
	var obj = setObj(n);
	if(nn5){
		obj.visibility = "show";
	}else{
		obj.style.visibility = "visible";
	}
	activeLayer = obj;
}

function layerOff(){
	if(activeLayer != null){
		if(nn5){
			activeLayer.visibility = "hide";
		}else{
			activeLayer.style.visibility ="hidden";
		}
	activeLayer = null
	}
}

activeLayer = null