Hi Laurent,
If you open AO and run Find for "IBP" or "ERP" it will show you those 3 Workbooks.
To move data there are push buttons that are tied to Planning Sequences (Functions). Those Functions are implemented as FOX formulas. Those FOX formulas contain FM calls that read/write data from/to ERP using BAPIs.
It's a natural function of FOX to read/write data to Real Tim Cubes.
Regards,
Gersh