[erlang-questions] gen module documentation availability

[Ciprian Dorin, Craciun]

    Hello all!

    I've seen that gen_server, gen_fsm and gen_event, are all based on
the module gen... Now I've also seen that this module is not specified
in the official documentation...

    My questions are:
    * can I use this module without fear that it could (one day) be
modified in an incompatible way? (I want to build a custom
servlet-like process framework, and I would have used it directly
without passing through gen_server);
    * is it documented anywhere more than the source code? (I mean are
there some examples?);

    Thanks,
    Ciprian Craciun.