if ($graph_params->visible('previous')) {
        $rrd_options .= ' DEF:' . $i . 'X=' . $rrd['filename'] . ':' . $rrd['ds'] . ':AVERAGE:start=' . $prev_from . ':end=' . $from;
        $rrd_options .= ' SHIFT:' . $i . "X:$period";
        $thingX .= $seperatorX . $i . 'X,UN,0,' . $i . 'X,IF';
        $plusesX .= $plusX;