Answer:
An open facility is one in which security is based on staff involvement, where doors are often not locked, and there is no perimeter fencing or walls.
Step-by-step explanation:
As it is stated, there are some open facilities, which rely on no other security measure than staff involvement, such as security guards who control the area. An example of open facility can be a public building which is available at all times during the day such as a library, a museum, etc.