How does one obtain roman numerals for chapter numbers in a quarto book?

[n8craig]

Description

Starting with a generic quarto book, how does one obtain roman numerals for chapter numbers?

Apologies in advance if I'm missing something in documentation, or an example in the wild--but I'm unclear how to control chapter numbering style. From the sample gallery, the volume Hands On Programming in R has letters for appendices, but I don't see anything special in the book's _quarto.yml.

---
crossref:
  chapters: true
  labels: roman
---

Putting the above in _quarto.yml makes H1 a chapter if I add another H1 item on any page. However, that new chapter is not included in sidebar. Additionally, chapter labels are still alpha but if I add a figure then figure labels are roman.

In the documentation on cross-references, I see discussion of how to change figure, table, and other kinds of labels but not chapter. Likewise, documentation on custom reference types provides examples of videos, but I'm not sure how this might be applied to customize chapter numbering.

How would one set the chapter labels to anything other than the default alpha? Thanks in advance.

[mcanouil]

What defines chapters numerals is being a "chapter" or an "appendix":

• https://github.com/jjallaire/hopr/blob/ef0c5b32ae2f60d17fa1a1e21a8f6ea57da6a548/_quarto.yml#L33

I don't think you can control this, at least for html based formats.