exit devices (Also called panic device, panic hardware, panic bolt and crash bar.) Is a type of locking device that has an inside bar to open the door.
When depressed, the release bar (crossbar, push pad, etc.) retracts the latch bolt, permitting the door to be opened.
Building codes require that the activating portion of the release mechanism extend not less than half way across the door.
A dogging device allows the release bar to be locked down so that the latch bolt remains retracted and the door can be used as for free access. They may or may not be key operated from the outside.
A dogging device may not be used on fire doors.