function toggle(id) {
   var el, symbol;
   
   try {
     el = document.getElementById(id);
     symbol = document.getElementById(id + "symbol");
     if ('inline' != el.style.display) {
       el.style.display = 'inline';
       symbol.innerHTML = '-';
     } else {
       el.style.display = 'none';
       symbol.innerHTML = "+";
     }
     
   } catch(e) {
   }
   
   return false;
 }