public function getUsedFields()
    {
        if (empty($this->usedFields)) {
            $this->usedFields = [];
            foreach (AddressField::getAll() as $field) {
                if (strpos($this->format, '%' . $field) !== false) {
                    $this->usedFields[] = $field;
                }
            }
        }

        return $this->usedFields;
    }