.IS1 File Extension

Data file created by M3 Sakura, a loader for the Nintendo DS that runs on the M3DS Real and M3i Zero flashcarts; stores the state of a game as it is played; used for saving game snapshots, even when the game does not allow you to save at that time.

M3 Sakura save slots also use extensions such as ".is0," ".is2," and ".is3."

File used by Synergex's ISAM (Indexed Sequential Access Method) File Maintenance Utility (isutil), a file indexing program that is part of the Synergy/DE software; contains indexed information used for fast file lookup.