When using Xiqual to initialise SDL, several subsystems can be started at once, including a few external libraries.
The default initialisation start sound, graphics and input. If SDL_mixer and SDL_ttf are available, they are also opened. When xi_init() returns successfully, you can start straight away to draw on the screen in the global structure, make noise with Mix_* functions and open TTF fonts (plus other formats supported by this library).
The global structure holds the actual audio format specs.
If you want to use the LUI interface subsystem, pass the tag XI_LUI to xi_init() with any data. If XIF_USE_LUI is set in the global structure's flags, full use of LUI is available. It is very unlikely to fail, as all lui_init() does is to allocate a surface for a 4x4 pixmap.
Unlike kicking a heroin or tobacco addiction, quitting Xiqual is very easy. Just call xi_quit() to have SDL, SDL_ttf, SDL_mixer and LUI subsystems deallocate their resources. All gadgets and other resources created with Xiqual are freed.