I/O zone
    An I/O zone is a zone entity in which the I/O linking can be
            spread across multiple Synergis™ units, while one unit acts as the master unit. All
            Synergis™ units involved in an I/O zone must be managed by the same Access Manager. The
            I/O zone works independently of the Access Manager, but ceases to function if the master
            unit is down. An I/O zone can be armed and disarmed from Security Desk as long as the
            master unit is online.