My Dahua NVR is running V4 software. There are two icons on the main live view screen that are next to the timestamp. See screen closeup snapshot below.

I know what the Bell icon does (alarm Arming/Disarming function). But next to it is a broken half circle with arrowheads. A "W" toggles in the center of the circle when I click it. What is this function called and what does this do?
I've searched the NVR manual and tried my friend Mr. Google, no joy. No doubt a member here will solve this mystery so I can rest easy at night knowing what it does.
- Thomas

I know what the Bell icon does (alarm Arming/Disarming function). But next to it is a broken half circle with arrowheads. A "W" toggles in the center of the circle when I click it. What is this function called and what does this do?
I've searched the NVR manual and tried my friend Mr. Google, no joy. No doubt a member here will solve this mystery so I can rest easy at night knowing what it does.
- Thomas