function rollup() {
    if ( document.getElementById('nav') ) {
        var parent = document.getElementById('nav');
        // initialize
        var dts = parent.getElementsByTagName('dt');
        var dds = parent.getElementsByTagName('dd');
        for ( var i = 0; i < dds.length; i++ ) {
            var name = dds[i].className;
            if ( name != 'current' ) {
                dds[i].className = 'hidden';
            }
        }
        // attach events
        for ( var i = 0; i < dts.length; i++ ) {
            dts[i].className = 'trigger';
            dts[i].onclick = function( evt ) {
                var element = this.nextSibling;
                while ( element && element.nodeType != 1 ) {
                    element = element.nextSibling;
                }
                var swap = element.className;
                element.className = (swap == '') ? 'hidden' : '' ;
            }
        }
    }
}

function toggle( id ) {
    if ( document.getElementById( id ) ) {
        var element = document.getElementById( id );
        var swap = element.className;
        element.className = (swap == '') ? 'hidden' : '' ;
    }
}

function addEvent(elm, evType, fn, useCapture){
    if (elm.addEventListener){
        elm.addEventListener(evType, fn, useCapture);
        return true;
    } else if (elm.attachEvent) {
        var r = elm.attachEvent('on' + evType, fn);
        return r;
    } else {
        elm['on' + evType] = fn;
    }
}
addEvent(window, 'load', rollup, false);