function back()
  {
   top.close();
  }

function LoadExt(url)
  {
   ExternWin = window.open(url,'EXTERN',"width=900,height=600,resizable=yes,scrollbars=yes,toolbar=yes,status=yes,menubar=yes,personalbar=yes,location=yes");
   if(ExternWin == null){
       return false;
   }
   ExternWin.focus();
  }