One of the most common issues in remote file service is receiving a "modified original" instead of a true stock file. This creates serious calibration risks because the engineer cannot accurately identify the factory baseline.
A genuine original file is the ECU data as it was set by BMW at the factory (or after an official software update). It contains the manufacturer's calibration maps, limiters and safety parameters in their intended state.
A modified file is any read taken from an ECU that has been previously calibrated — even if it was later "reverted" using a stock file from a database. Database stock files may not match your specific DME variant, production date, or market adaptation.