On November 18, 2017 5:18:10 PM GMT+00:00, Nicolas Goaziou 
>I see. I don't think UNNUMBERED should be able to modify the structure
>of the document. I suggest to write a parse tree filter that does that
>change to the tree.
>
>Regards,

Please note: it is not UNNUMBERED that modifies the structure in my suggestion but rather SKIP-OUTLINE-LEVEL.