function acl_user_agent($cdn_acl_user_agent="") {
        if ($this->cfs_http->getCDNMUrl() == NULL) {
            throw new CDNNotEnabledException(
                "Authentication response did not indicate CDN availability");
        }
        list($status,$reason) =
            $this->cfs_http->update_cdn_container($this->name,
                                                  $this->cdn_ttl,
                                                  $this->cdn_log_retention,
                                                  $cdn_acl_user_agent,
                                                  $this->cdn_acl_referrer
                );
        if (!in_array($status, array(202,404))) {
            throw new InvalidResponseException(
                "Invalid response (".$status."): ".$this->cfs_http->get_error());
        }
        $this->cdn_acl_user_agent = $cdn_acl_user_agent;
        return True;
    }