: Likely a unique internal game identifier or shorthand (e.g., related to Chuckie Egg or a similar title).
The primary feature of a "Decr" (Decrypted) file is its on emulators. While retail games are typically encrypted to prevent unauthorized use, a decrypted .3ds or .cia file allows you to bypass the technical steps usually required to "dump" your own keys from a physical console.
: May stand for "Serial Number" or a specific release type (e.g., "Standard Edition" or "Special Edition"). JPN : Indicates the Japanese region version of the software.