function toggleUnit(parent, id)
{
    var element = document.getElementById(id);
    if (element.style.display == "none")
    {
        element.style.display = "";
        parent.innerHTML = '<image src="/images/arrow-down.gif" />';
    }
    else
    {
        element.style.display = "none";
        parent.innerHTML = '<image src="/images/arrow-right.gif" />';
    }
}