These locks are intended to help prevent children from accidentally opening the rear doors. Use them on both rear doors whenever a child rides in the rear seat of the vehicle.
If you slide the child safety lock to the lock position before closing that door, the door cannot be opened from the inside. The door can only be opened by pulling the outside handle.

Locking, Unlocking with Door- Lock Knob
Trunk LidMazda 6 Owners Manual: Selector cable adjustment
1. Remove the center console.
2. Shift the selector lever to P position.
3. Unlock the lock piece of the selector cable (selector lever side) in the
order shown in the figure.
4. Verify that the manual shaft is in P position.
5. Lock the lock piece of the selector cable (selector lever side) ...
Mazda 6 Owners Manual: Service warnings
HANDLING REFRIGERANT
Avoid breathing air conditioning refrigerant or lubricant vapor.
Exposure may irritate eyes, nose and throat. Also, due to environmental
concerns, we urge use of recovery/recycling/recharging equipment when
draining R-134a from the air conditioning system. If accide ...