One in, one out policy
Appearance
![](http://upload.wikimedia.org/wikipedia/commons/thumb/d/d3/Warning_signs_on_the_door_-_one_person_in%2C_one_person_out.jpg/220px-Warning_signs_on_the_door_-_one_person_in%2C_one_person_out.jpg)
A one in, one out policy is a method used to control the number of people in one place or building at any one time. Where a place or building has reached its maximum capacity, further entry is only allowed upon a person leaving. It is especially used in nightclubs and bars, and most military establishments.
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