RAC (Restore Animal Crossing) is a tool for backing up and restoring the player's town between an Animal Crossing: Wild World Game Card and a SLOT-2 device.
It can be used to revert a town that has been "seeded" by online vandals, to manage multiple towns with one Game Card, or to copy a town to a PC for use with cheating tools.
Backed-up towns go in the folder
/data/acww/, with the file's name based on the name of the town plus the current date.
RAC can also back up and restore the saved data of other games with a type 3 save 256 KiB in size, such as Mario Kart DS and Mario vs. Donkey Kong 2: March of the Minis, albeit without the convenient automatic naming feature.
 SLOT-1 caveat
RAC has been successfully tested with GBA Movie Player (Compact Flash) and SuperCard (SD Card). But RAC, eepinator, and other tools that copy save data between a file system and a Game Card in SLOT-1 do not work with many SLOT-1 devices, such as R4TF and DS-Xtreme, because these cards generally do not allow file system access if they are inserted into a powered-on DS. Users of these devices should use Savsender instead to back up save data over the wireless connection.