The continuum

Three formats: none, timeline, spectrum. Pick the axis the book lives on.

A flat sequence is fine when order is the only structure. A timeline adds a `year` to every page and renders a decade axis the reader can scrub. A spectrum places every page on a −N..+N integer axis with palette shifts as you cross stops — useful when the book is about a continuum (left/right, secular/religious, denying/integrating). The same outline format works for all three. You pick once at scaffold time, and you can change later.