The Trigger component is used by the Railcam2DCore component to manage the camera's Rail connections. When the Trigger detects its Target, the Trigger's TargetDetected value becomes true.
The Railcam2DCore component is able to see this change, and so performs the Trigger's Event. The Event consists of either connecting or disconnecting the camera from the Trigger's Selected Rail. The Core then sets the Trigger's TargetDetected value back to false.