Parts numbering in a quarto book

[xtimbeau]

Description

There are some discussions about reseting numbering of chapters per part (#1284 or #5987 for instance). One suggestion would be to be able to number part, hierarchally, and chapters inside. By the way a third level would be nice too (sub-chapters ? #2504).
The numbering could be specified A.1 for part I, chapter 1, and B.1 for chapter 1 of part B, instead of chapter 1 and chapter 2.

[mcanouil]

Is it a question or a feature request?

It seems to be the same as:

• Parts in quarto book #815