outline-minor-mode is an interactive autoloaded compiled Lisp function in `outline.el'.

(outline-minor-mode &optional ARG)

Toggle Outline minor mode.
With a prefix argument ARG, enable Outline minor mode if ARG is
positive, and disable it otherwise. If called from Lisp, enable
the mode if ARG is omitted or nil.

See the command `outline-mode' for more information on this mode.