public function setZone(string $zone = "B") : CNabuDataObject
    {
        if ($zone === null) {
            throw new ENabuCoreException(
                    ENabuCoreException::ERROR_NULL_VALUE_NOT_ALLOWED_IN,
                    array("\$zone")
            );
        }
        $this->setValue('nb_site_map_role_zone', $zone);
        
        return $this;
    }