function setFocus3(i)
{
 selectLayer3(i);
}
function selectLayer3(i)
{
 switch(i)
 {
 case 1:
 document.getElementById("N1").style.display="block";
 document.getElementById("N2").style.display="none";
 break;
 case 2:
 document.getElementById("N1").style.display="none";
 document.getElementById("N2").style.display="block";
 break;
 }
}