2.4.6 is the AA success criterion that says "Headings and labels describe topic or purpose".

While this makes sense for labels, and for books with topic-based chapters, how a novel chapter heading describes its topic or purpose isn't immediately clear in a lot of cases. It's questionable if a chapter number alone describes either a topic or purpose (short of an argument that the Xth chapter's purpose is to be in position X).

I finally got around to opening an issue about this in the WCAG tracker, and it seems the intent of the success criterion doesn't exactly match its wording, but it's also complicated to change the SC text now.

The general response I've gotten, though, is that the presence of a heading establishes the context of its chapter (if not a specific topic or purpose) and that's enough to satisfy the SC, so it's never actually an issue for publications.

Should we document this in the techniques document, though, so we have it as a reference?