public function original_headers() {
        return array(
            '', // For filter icon.
            get_string('assessmentname', 'gradereport_singleview'),
            get_string('gradecategory', 'grades'),
            get_string('range', 'grades'),
            get_string('grade', 'grades'),
            get_string('feedback', 'grades'),
            $this->make_toggle_links('override'),
            $this->make_toggle_links('exclude')
        );
    }