🚀 go-pugleaf

Hello Doug,
As I said:
"I think this scheme should work if a Part is a file, and Section1 starts a file containing the other subsections."

You have two options here - split files in a book so that no file contains more than one Section 1; or, if you must have multiple Sections 1 in the same file, you need to move the numbering scheme one step back, that is use <$chapnum> for the part and then
For Section1 setup Heading2 autonumbering as H:<$chapnum>.<n+>
For Section1.1 setup autonumbering as H:<$chapnum>.<n>.<n+>
For Section1.1.1 setup autonumbering as H:<$chapnum>.<n>.<n>.<n+>

This is because the <$chapnum> variable is updated within a book and not within a file.

A third alternative is to use a numbering scheme that would have been used in previous versions of FM before <$volnum>, and <$chapnum> came on the scene. That is use the first instance of <n> to represent part numbers and cascade all other autonumbering definitions to include Part and Section text strings.

There's a fourth alternative that involves putting the Part number, even the top Section number in running headers or footers, then including subsets of heading numbering in the actual headings in the body text.

FM offers lots of flexibility for numbering schemes, you just need time, understanding, and permissions to change the templates.
Cheers
Ian