Furuno FCR-2107 Operator's Manual page 274

Areas
To include areas in the chart alert, check the Danger Area box in the Area page of the Plan User Chart dialog box.
Danger Area must checked, otherwise danger areas of a user chart cannot not be used in the chart alert. The
dangerous area is drawn in red instead of dark yellow (color may be different depending on Palette in use).
In the Area page, you can
include areas in the chart alert
by checking Danger Area.
The figure below shows the behavior of a dangerous symbol, line and area in the chart alert check.
Presentation of
Dangerous Area
Presentation of
Dangerous Symbol
Presentation of
Dangerous Line
9-6
9. Chart Alerts