SDL_USEREVENT clarification needed


The manual here:

says that SDL_USEREVENT is for my own use. But then it says it should be allocated using SDL_RegisterEvents(). SDL_RegisterEvents(); seems to return SDL_USEREVENT. But this isn’t mentioned anywhere. Can I rely on this?

Why does SDL_USEREVENT even exist as a pre-defined value, if SDL_RegisterEvents() is supposed to be used to obtain it?