function isValidCode ()
{
  var v = GetObjectByRef ("Confirm");
  if (v == null)
    return true;
  v = v.value;
  return Math.floor (v / 100) % 97 == (v % 100);
}
function isFieldFilled (f)
{
  return GetObjectByRef (f).value != "";
}
function isFilled ()
{
  return isValidCode () && isFieldFilled ("Name") && isFieldFilled ("Email");
}
function SetInfo (id, info, valid)
{
  var o = GetObjectByRef (id);
  if (o == null)
    return;
  o.innerHTML = valid ? "": info;
}
function checkCode (obj)
{
  SetInfo ("Check", "Dit is een ongeldige code", isValidCode ());
  SetInfo ("CheckName", "Dit veld is vereist", isFieldFilled ("Name"));
  SetInfo ("CheckEmail", "Dit veld is vereist", isFieldFilled ("Email"));
  var o = GetObjectByRef ("Send");
  if (o != null)
    o.style.display= isFilled () ? "inline" : "none";
}