Fire doors are required to have an active latchbolt, so fire exit hardware (panic hardware for fire doors) is not equipped with a mechanical dogging mechanism that could be used to hold the latch retracted. When the lack of dogging creates an inconvenience, creative modifications sometimes occur. The added slidebolt on this fire exit hardware will prevent the fire door from functioning properly during a fire. I wonder what the insurance company would have to say about that.
Thank you to Dave Rogers from Bell Hardware of Portland for the photos!