function updateDays(form)
    {
      year = parseInt(form.year.options[form.year.selectedIndex].value);
      month = form.month.selectedIndex;
      day = form.day.selectedIndex;
      form.day.options.length = 0;
      var days = new Array(31, ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0 ? 29 : 28), 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
      for(i = 0; i < days[month]; i++)
      {
        form.day.options.length = form.day.options.length + 1;
        form.day.options[i].value = i + 1;
        form.day.options[i].text = i + 1;
      }
      form.day.selectedIndex = (day < form.day.options.length) ? day : form.day.options.length - 1;
    }