The fuel standards around the world and how they are expressed to the public had confused me for some time The basics are below. There are more complex descriptions available online for those who want more details
The standards in each country include requirements on minimum RON and MON but "at the pump" when purchasing fuel, each country is using a different item in the standards to indicate the grade of fuel.
In Australia we use RON where the US uses AKI so a US 87 octane is equivalent to 91 in Australia.
In the US there is no national standard unlike Australia and the EU. The SAE sets a definition only.
There is considerable confusion and misinformation about use of ethanol blended fuels. Ethanol increases octane rating and "burns" cleaner. The problems with it are the differences in engine residues after combustion and whether fuel storage and delivery systems are rated to handle ethanol rather than the claims of additives needed to be able to use ethanol causing problems. Emotions not facts, figures and logic are driving outlooks.
The ethical concerns with regard to turning productive farmland from food to fuel production and the efficiency of current production methods are issues separate to engine combustion efficiency and should be the real debate.
BMW have specified that all the motorcycle range is rated for use of ethanol blends of up to 10%.
RON 95 was specified for the original 650GS then in late 2001 BMS-C programming was introduced to allow the use of RON 91. The BMS-C requires reprogramming to change the fuel grade. On these single spark models the only way to know which fuel to use is to check the program and data version of the firmware in the BMS-C.
The BMS and Socket information pdf in Utilities/Diagnostics has information on the firmware versions.
The dual spark F650GS and G Series including the Sertao are all programmed for RON 91.