There are several simple functions implemented in this file, like file_fopen, file_close, which are obvious. On the other hand you can find functions, like file_chown, which is not obvious at all under Windows NT.
You can find almost all system functions that you need implemented in this file running on Windows NT as well as on UNIX.
The module is GNU LGPL and is part of the ScriptBasic interpreter package.
For further information visit the ScriptBasic home page and read the Developers' Guide detailing all the modules.