The most important files are the Map of Europe and the Junction View for basic navigation.

sdcard /map/YourMapofEurope.img
sdcard /map/Europedem.img (optional)
sdcard /map/Europe3D.img (optional)

sdcard /Garmin/JCV/YourJCVofEurope.JCV

See also for more detailed explanations.
[Only registered and activated users can see links. ]