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: Emergency Locking Mode
When the seat belt is fastened, it will always be in the emergency locking mode. In the emergency locking mode, the belt remains comfortable on the occupant and the retractor will lock in position during a collision.
If the belt is locked and cannot be pulled out, retract the belt once, and then ...
Mazda 6 Owners Manual: Installing Child-Restraint Systems
Accident statistics reveal that a child is safer in the rear seat. The front
passenger's seat is clearly the worst choice for any child under 12, and with rear-facing
childrestraint systems it is clearly unsafe due to air bags.
NOTE
Even if your vehicle is equipped with front passenger occupan ...