what is the advantage of define-minor-mode (was: define-minor-mode does not add entry into modeline)

Ben> it *should* add it to the modeline. this is accomplished using Ben> add-minor-mode, which is called by define-minor-mode. it's possible Ben> that, if you're dynamically changing things, you won't see the change Ben> till you delete a buffer and revisit it. So I did some testing, not finished yet, there are incompatibilities with longlines.el which uses define-minor-mode and older pkg such as appt.el. (I still don't know why). Before I proceed a important question what is the advantage of using define-minor-mode over the *old* way of defining a minor mode?