The rear armrest in the center of the rear seatback can be used (no occupant in the center seat) or placed upright.

WARNING
Never put your hands and fingers around the moving parts of the seat and armrest:
Putting your hands and fingers around the moving parts of the seat and armrest is dangerous as they could get injured.
Split Folding
Head RestraintsMazda 6 Owners Manual: Declaration of Conformity
Keyless Entry System/Immobilizer System
Blind Spot Monitoring (BSM) System
NOTE
During printing time of this user manual the approvals listed above are granted.
WARNING
Change or modifications not expressively approved by the party responsible
for compliance could void the use's authori ...
Mazda 6 Owners Manual: Picture Quality Adjustment
WARNING
Always adjust the picture quality of the rear view monitor while the vehicle
is stopped: Do not adjust the picture quality of the rear view monitor while
driving the vehicle. Adjusting the picture quality of the rear view monitor such
as brightness, contrast, color, and tint while dri ...