Octane Confusion

I have a couple questions regarding octane
1. Have you ever heard of the R+M/2 method for rating octane ? its every where over here. lowest= 87 mid-grade=93 premium= 98 (the pumps where i live have only those three options
)
2. Does it make sense to make an engine for the European market on 98 octane and then in order to market those same engines in the U.S, kick the octane down to 91 (RON) and lower the compression to make the engine run with that octane ? ( I am struggling with this concept for some reason
)
1. Have you ever heard of the R+M/2 method for rating octane ? its every where over here. lowest= 87 mid-grade=93 premium= 98 (the pumps where i live have only those three options

2. Does it make sense to make an engine for the European market on 98 octane and then in order to market those same engines in the U.S, kick the octane down to 91 (RON) and lower the compression to make the engine run with that octane ? ( I am struggling with this concept for some reason
