Re-installing wheel

[Fipp]

My manual for 2016 FC says the following on page 8-7....

“ WARNING !
when removing aluminum forged wheels from spindle, it is very important to mark them to ensure the wheel is placed in the same position of the drum when reinstalling. If the aluminum forged wheel is to be mounted on a different drum, it is important to sand all loose corrosion from the mating surfaces. “

What does that mean?! Is it obvious and I’m not getting it?
Getting ready to replace tires on existing wheels and saw this warning in the manual.

Thanks

[rmkrum]

Corrosion where the aluminum wheel meets the iron brake drum will build up and cause the wheel to sit wrong or not seat tightly in place.
Marking position helps avoid loosening when the wheel is re-installed. If it’s necessary to change positions entirely, cleaning off all the corrosion lets the wheel seat properly. Both the wheel and mating surface needs to be clean of any loose ‘stuff’ or built-up rust or corrosion to seat properly.

Don’t forget to use a calibrated torque wrench to install the lug nuts, and recheck the torque at the intervals suggested by the place you bought the tires at, and at intervals listed in the manual.

[AtomicNo13]

Corrosion will sometimes not allow the mating surfaces to sit perfectly flush and the rim can develop a wobble.
Most better tire shops will use a wire wheel to clean the surfaces.

[GCinSC2]

A tire shop that is trying to follow good practices will use a small buffer that has a material like scotch brite pad on it to clean the mounting surfaces hub to wheel.