Guide lines which indicate the width of the vehicle (yellow) are displayed on the screen as a reference to the approximate width of the vehicle in comparison to the width of the parking space you are about to back into.
Use this display view for parking your vehicle in a parking space or garage.

a) Vehicle width guide lines (yellow)
These guide lines serve as a reference to the approximate width of the vehicle.
b) Distance guide lines.
These guide lines indicate the approximate distance to a point measured from the vehicle's rear (from the end of the bumper).
CAUTION
The guide lines on the screen are fixed lines. They are not synced to the driver's turning of the steering wheel. Always be careful and check the area to the vehicle's rear and the surrounding area directly with your eyes while backing up.
Displayable Range on the Screen
Rear View Monitor OperationMazda 6 Owners Manual: Cruise control switch inspection
1. Disconnect the negative battery cable.
2. Remove the driver-side air bag module. (See DRIVER-SIDE AIR BAG MODULE
REMOVAL/INSTALLATION.)
3. Disconnect the cruise control switch connector.
4. Inspect for resistance and continuity between the cruise control switch
terminals using an ohmmeter. ...
Mazda 6 Owners Manual: Front seat disassembly/assembly
Warning
Handling the front seat (side air bag) improperly can accidentally
deploy the side air bag, which may seriously injure you. Read AIR BAG SYSTEM
SERVICE WARNINGS before handling the front seat. (See SERVICE WARNINGS.)
1. Disconnect the negative battery cable and wait for more tha ...