LevelOne NVR-0216 - Manual (Page 79)

[NVR MANAGEMENT SOFTWARE USER MANUAL] 79
The sub map provides the PIP (Picture-in-Picture) view, which the
main map is embedded in the sub map so that users can still know if
there are events being triggered from other NVRs at the same time.
Simply double-clicking the embedded main map to go back to the
main map view.