Looking though the .dll that's included on the SD, there are LOTS of informative strings in here. Like this one: "MAP_UNLOCK: Unlock files do not match SD Card." And "MAP_UNLOCK: Error deleting unlock files, is SD card locked?" So, those prove that the .unl files are "Unlock files", and that they are tied to the SD card. (I hadn't seen these things commented on before. if there is a thread somewhere about hacking the software, or reverse engineering the UNL file contents, please point me to it!).