public function setAttachment(string $attachment = "F") : CNabuDataObject
    {
        if ($attachment === null) {
            throw new ENabuCoreException(
                    ENabuCoreException::ERROR_NULL_VALUE_NOT_ALLOWED_IN,
                    array("\$attachment")
            );
        }
        $this->setValue('nb_site_target_attachment', $attachment);
        
        return $this;
    }