That documentation / list is interesting. They say that logind is fully documented for example. But if you follow the link, you get things like:

    CreateSession(in  u arg_0,
                    in  u arg_1,
                    in  s arg_2,
                    in  s arg_3,
                    in  s arg_4,
                    in  s arg_5,
                    ...

With no further explanation, apart from one paragraph summary of who shouldn't call it.

I remember someone complaining about that years ago already. Apparently nothing changed.