"Master boxes", BTW are improved manual Pull Boxes (the shed type) with a spring loaded rotating arm on the inside of the box, kept in the "cocked" position by a solenoid.
When the (newer) building alarm system trips, the solenoid retracts, allowing the small arm to rotate, tripping the "PULL" hook in the fire box, sending the coded alarm for that location.
Until the inside alarm is reset (or the zone is disabled, allowing reset of the interior panel), the spring loaded arm won't latch, since the solenoid is still withdrawn.
(The Great Lakes Naval Training Center used to have that combination, and it was there that the difference between simple "pull boxes" and "master boxes" was explained to me.)
