function popupSub(e,div_id) {
        // make sure no sub listing is shown
        var tmp = document.getElementById('AClist');
        tmp.style.display="none";
        tmp = document.getElementById('CFlist');
        tmp.style.display="none";
        tmp = document.getElementById('FMlist');
        tmp.style.display="none";
        tmp = document.getElementById('MSlist');
        tmp.style.display="none";
        tmp = document.getElementById('SZlist');
        tmp.style.display="none";
        
        // show desired sub listing
        var o = document.getElementById(div_id);
        var y = 0;;
        
        if (document.all) {
            y = event.clientY + document.body.scrollTop -30;
            x = event.clientX + document.body.scrollLeft +15;
        } else {
            y = e.pageY -30;
            x = e.pageX +15;
        }
        o.style.position="absolute";
        o.style.top = y + "px";
        o.style.left = x + "px";
        o.style.display = "block";
    }

    function popoutSub(div_id) {
        var o = document.getElementById(div_id);
        o.style.display = "none";
    }