function item(id_max, selected) {
  if (! document.getElementById) return;
  for (i = 0; i <= id_max; i++) {
    if (! document.getElementById("item" + i)) continue;
    if (i == selected) {
      document.getElementById("item" + i).style.display = "block";
    } else {
      document.getElementById("item" + i).style.display = "none";
    }
  }
}
function description(id_max, selected) {
  if (! document.getElementById) return;
  for (i = 0; i <= id_max; i++) {
    if (! document.getElementById("description" + i)) continue;
    if (i == selected) {
      document.getElementById("description" + i).style.display = "block";
    } else {
      document.getElementById("description" + i).style.display = "none";
    }
  }
}