If your vehicle rapidly closes in on the vehicle ahead because the vehicle applies the brakes suddenly while you are traveling in headway control, the warning sound activates and the brake warning is indicated in the display. Always verify the safety of the surrounding area and depress the brake pedal while keeping a safer distance from the vehicle ahead.
Additionally, always keep a safer distance from the vehicles behind you.

Mazda Radar Cruise Control (MRCC) Display Indication
Setting the SystemMazda 6 Owners Manual: Sst
Some Ford SST or equivalent are used as SSTs necessary for
engine repair. Note that these SSTs are marked with Ford SST
numbers.
Note that a Ford SST number is written together with a
corresponding Mazda SST number as shown below.
Example (section ST)
Example (except section ST)
...
Mazda 6 Owners Manual: Washer Fluid
Inspecting Washer Fluid Level
WARNING
Use only windshield washer fluid or plain water in the reservoir:
Using radiator antifreeze as washer fluid is dangerous. If sprayed on the windshield,
it will dirty the windshield, affect your visibility, and could result in an accident.
Using Washer Flu ...