I have 8 file of the oof type in my main Descent 3 folder. ALL of them are due to custom mods that have been used with some levels and some custom MP games. Most have not been used in quite a while.
ALL of them are due to custom mods that have been used with some levels and some custom MP games.
The files are useless in SP and on clients, hence a machine that's not used for hosting servers (either dedis or in-game) shouldn't have any oof files in Descent 3's main folder.
As you may be aware (no, I'm sure you're aware) most resources and custom items provided by a server for an Descent 3 MP game must be downloaded to each of the client/player computers in order for that custom mod/resource/option will be seen/used by the players (custom ships, custom weapons, custom functions/actions/visuals, custom sounds, etc.).
These oof files provide special custom items not normally provided by the standard copy of Descent 3, therefore it makes complete sense that the clients/players would be either downloading those things, or having them installed in advance of seeing or using those custom features.
For example, when participating with some MP games in connection with the Descent Fan Fiction, there was special custom games setup with custom ships fashioned after custom ships used in some of the stories posted there. Of the 8 .oof files in my Descent 3, I know for a fact that at least 5 of those .oof files are required in order for me (as a player, not the host/server) to be able to see and/or use those custom ships in game.