outline-head-from-level
outline-head-from-level is a compiled Lisp function in `outline.el
'.
(outline-head-from-level LEVEL HEAD &optional ALIST)
Get new heading with level LEVEL from ALIST.
If there are no such entries, return nil.
ALIST defaults to `outline-heading-alist'.
Similar to (car (rassoc LEVEL ALIST)).
If there are several different entries with same new level, choose
the one with the smallest distance to the association of HEAD in the alist.
This makes it possible for promotion to work in modes with several
independent sets of headings (numbered, unnumbered, appendix...)