public function preValidate(): bool
    {
        $this->errors = [];

        if (!\is_array($this->parsedfile)) {
            $this->errors[] = 'Incorrect format parsed file';

            return false;
        }

        $r = $this->readUNHmessageNumber();
        if (!$r && isset($this->errors[0]) && $this->errors[0] == 'Segment "UNH" is ambiguous') {
            $this->errors = [];
            $this->errors[] = 'File has multiple messages';

            return false;
        }

        return true;
    }