if (preg_match('/^.+?\\..+?\\..+$/', $this->cells['ref']->v)) {
            $ref_infos = explode('.', $this->cells['ref']->v);
            $this->cells['ref']->info = "The <code>{$ref_infos[2]}</code> column of table <code>{$ref_infos[1]}</code> is compared to
                                        <code>{$this->cells['key']->v}</code> key of table <code>{$this->cells['table']->v}</code>";
        }