Fg-optional-mp-files.bin [hot] Official

This file typically includes maps, assets, and binary code strictly required for multiplayer functionality .

In plain English: When you fly online in FlightGear, the simulator needs to download and display other pilots' aircraft models (3D shapes, textures, and sounds) in real-time. Storing this data in a binary format allows FlightGear to load these models much faster the next time you encounter the same aircraft. The .bin extension indicates it is a pre-processed, serialized data structure rather than human-readable text. fg-optional-mp-files.bin