Likely stands for "Region Free," suggesting the CIA file has been patched to work on any 3DS console regardless of its original region.
Because the original file was too large for a single upload, it was split into multiple parts using WinRAR. You need all parts (Part 1, Part 2, etc.) in the same folder to extract the final .cia file. Summary of the "Story"
Indicates the North American region version of the game.
Stands for Pokémon Super Mystery Dungeon , a 2015 role-playing game for the Nintendo 3DS.