Each part is numbered based on its place in the organization. Parts not preceded by a chapter (i.e. they are the only divisions under a title) are simply called part 1, 2, 3...
A part that is preceded by a chapter gets a three-digit number instead. Parts under chapter I are parts 100-199, parts under chapter II are parts 200-299, and so forth.
If the chapter has subchapters, the subchapter is indicated by the second digit. So subchapter A (all in chapter II) would have parts 210-219, subchapter B would have parts 220-229, and so forth.
Section numbers are indicated by both the part number and the section number, e.g. "§ 123.456" (section 456 of part 123).
The section number is normally one digit, but is increased to three digits (like part numbers) if they are preceded by subparts. For example, sections under subpart A of part 123 would be called § 123.100 through § 123.199, under subpart B they would be called § 123.200 through 123.299, and so forth.
Simply indicating the title and the section is sufficient for all references to provisions in the Code (plus any additional subsections).
↳Title (required) (Arabic numerals, e.g. "TITLE 3") ↳ Chapter (Roman numerals, e.g. "CHAPTER IV") ↳ Subchapter (uppercase letters, e.g. "SUBCHAPTER D") ↳ Part (required) (Arabic numerals, e.g. "PART 102") ↳ Subpart (uppercase letters, e.g. "SUBPART B") ↳ Section (required) (Arabic numerals, e.g. "§ 124.114")
(Of course, we could change the name of these if we want. E.g. article instead of subchapter, etc.)
Prefer to use optional divisions in this order:
However, if switching 1 and 2 makes sense then do that.