What are "Uni-directional" wheels?"

[GeeDee]

I suspect all have seen many SVXs and photos of SVXs that have the "uni-directional" OEM wheels mounted on the wrong side of the car. What damage or problems will occur from this incorrect installation? Is it incorrect?

If there are no negative consequences from mounting the wheels "backwards," why are they designated "uni-directional?"

NOTE: I'm asking only about the OEM WHEELS NOT TIRES!

Thanks in advance,

greg