Possibly the most well known of the tasks usually given to a security officer, and probably the most important of them, is the task of entry control, that of only allowing access by authorized personnel and keeping the property perimeter secure. Frequently not given the same consideration are the many duties and difficulties faced once the property is occupied, in this case that of exit control.
Safety codes usually require that exits are always open. This is contrary to proper security design; material taken through open fire exits can create massive losses. There are a few solutions that have been used to solve this issue. Some are hardware based, such as a panic button to lock the doors down for only enough time to fix the situation, keeping the doors open and thus in compliance most of the time. That however provides no security if the act is not caught as it happens.
Some solutions are more concrete, for example in the retail and restaurant businesses, alarms are sometimes attached and set off any time an exit-only door is opened. In many scenarios, such as high rises and secure office buildings, there may be no alternative to make sure the exit is unused than to have the exit screened at all times. Though the methods and approaches may vary, there is always a strategy to remove any bypass to the security system.