24-hour Sensors
any sensor in a system that cannot be disarmed or bypassed, such as fire detectors.

Access Code
a numeric combination that grants access to the system.

Access Control
Computerized and mechanical processes for limiting access to resources based on users' identities and predefined roles. May be integrated with intrusion and fire detection and access control.

Alarm
a device for signaling an emergency.

Antenna
a transmitting device that converts radio frequency energy into an electromagnetic field that travels through space, or a receiving device that converts an electromagnetic field in space into RF energy that can travel via a wire or cable.

Anti-Passback
An access control feature that prevents system users from giving their access codes or cards to someone else. A user code must be used to enter and then to exit before it can be used to enter again. Similarly, to prevent the same PIN from being used by several persons, a time delay can be programmed so the PIN won't work again until the time delay is complete.

Arm
to activate a security system so that its sensors detect changes of state and report those changes to a control panel.

Arming Levels
a set of instructions that determines which sensors are activated and which are not. All sensors would be armed when you are away from home, for example, but interior sensors would not be armed when you are home and moving around the house.

Asset Tracking
Software that enables control of physical assets, such as laptop computers and other high-value equipment. The system ensures that the cardholder requesting access is authorized to take assets through designated alarm points.

Auxiliary/Medical Alarm
an alarm signaling the need for medical personnel.