Every element takes the same shape of arguments — positionals, keywords (key=value), and boolean flags. A boolean is always named for its positive (on) sense and toggled with the sign: +name turns it on, -name turns it off (+numbered / -numbered, +listed / -listed), and a bare name means +name. There is never a negatively-named boolean to guess. The default is chosen per element, independent of the name: a positively-named boolean may default on — a <section> is listed and numbered, so you opt out with -listed / -numbered — or off — a <proof> is numbered only when you add +numbered.