function aff(id) {
    if (document.getElementById) {
      document.getElementById(id).style.visibility="visible";
    } else if (document.all) {
      document.all[id].style.visibility="visible";
    } else if (document.layers) {
      document.layers[id].visibility="visible";
    } } 
    
    function eff(id) {
    if (document.getElementById) {
      document.getElementById(id).style.visibility="hidden";
    } else if (document.all) {
      document.all[id].style.visibility="hidden";
    } else if (document.layers) {
      document.layers[id].visibility="hidden";
    } }