function toggleLayer(_w,_h) {
   var isIE=document.all?true:false;
   var isDOM=document.getElementById?true:false;
   var isNS4=document.layers?true:false;

   if (isDOM) {
      if (_h=='s') { document.getElementById(_w).style.display = 'block'; document.getElementById(_w).style.visibility='visible'; }
      if (_h=='h') { document.getElementById(_w).style.display = 'none'; document.getElementById(_w).style.visibility='hidden'; }
   } else if (isIE) {
      if (_h=='s') { eval("document.all."+_w+".style.display='block';"); eval("document.all."+_w+".style.visibility='visible';"); }
      if (_h=='h') { eval("document.all."+_w+".style.display='none';"); eval("document.all."+_w+".style.visibility='hidden';"); }
   } else if(isNS4) {
      if (_h=='s') { eval("document.layers['"+_w+"'].display='block';"); eval("document.layers['"+_w+"'].visibility='show';"); }
      if (_h=='h') { eval("document.layers['"+_w+"'].display='none';"); eval("document.layers['"+_w+"'].visibility='hide';"); }
   }
}

function switchLayer(_l1,_l2) {
   toggleLayer(_l1,'s');
   toggleLayer(_l2,'h');
}