function set_border_spacing($val)
    {
        $arr = explode(" ", $val);

        if (count($arr) == 1) {
            $arr[1] = $arr[0];
        }

        //see __set and __get, on all assignments clear cache, not needed on direct set through __set
        $this->_prop_cache["border_spacing"] = null;
        $this->_props["border_spacing"] = "$arr[0] $arr[1]";
    }