Background: ISO 32000-1, 14.8.4.2 Grouping Elements, page 583-584

Grouping element types considered:

- Sect
- Div

Other more specific grouping elements (Blockquote, Caption, TOC etc. intentionally left aside)

Is it correct to assume that 

- a Document can have as its children grouping entries of all types (Part, Art, Sect or Div)?

- a Part can have as its children only other grouping entries of type Art, Sect or Div?
- a Part can have as its children only other grouping entries of type Sect or Div?

- a Part can have as its children only other grouping entries of type Div?
Or could 

- Art have a child of type Part?

- Sect have a child of type Art or Part?
- Div have a child of type Sect, Art or Part?

Which of the following are legal, not legal or maybe legal but not recommended (the combinations below assume that any block level elements can only exist in the grouping entries at lowest child/nesting level):

- Document (once)

- - Part (one or more instances inside parent)
- – - Art (one or more instances inside parent)
- – - – Sect (one or more instances inside parent)
- – - – - Div (one or more instances inside parent)

- – - – - – BLSE based content H1 … Hn, P, …

- Document (once)
- – Part (one or more instances inside parent)

- – - H

- – - BLSE based content
- – - Art (one or more instances inside parent)
- – - – H
- – - – BLSE based content
- – - – Sect (one or more instances inside parent)
- – - – - H
- – - – - BLSE based content
- – - – - Div (one or more instances inside parent)
- – - – - – H

- – - – - – BLSE based content  P, …

- Document (once)
- – Part (one or more instances inside parent)
- – - H
- – - BLSE based content
- – - Art (one or more instances inside parent)
- – - – H
- – - – BLSE based content
- – - – Sect (one or more instances inside parent)
- – - – - H
- – - – - BLSE based content
- – - – - Div (one or more instances inside parent)
- – - – - – H
- – - – - – BLSE based content  P, …

- – - – - – Div (one or more instances inside parent)
- – - – - – - H
- – - – - – - BLSE based content  P, …

- – - – - – - Div (one or more instances inside parent)
- – - – - – - – H 
- – - – - – - – BLSE based content  P, …

- Document (once)
- – Art (one or more instances inside parent)
- – - Sect (one or more instances inside parent)
- – - – Div (one or more instances inside parent)
- – - – - BLSE based content

- Document (once)
- – Part (one or more instances inside parent)
- – - Sect (one or more instances inside parent)
- – - – Div (one or more instances inside parent)
- – - – - BLSE based content

- Document (once)
- – Part (one or more instances inside parent)
- – - Art (one or more instances inside parent)
- – - – Div (one or more instances inside parent)
- – - – - BLSE based content

- Document (once)
- – Part (one or more instances inside parent)
- – - Art (one or more instances inside parent)
- – - – Sect (one or more instances inside parent)
- – - – - BLSE based content

- Document (once)

- – Sect (one or more instances inside parent)
- – - Div (one or more instances inside parent)
- – - – BLSE based content

- Document (once)
- – Part (one or more instances inside parent)
- – - Div (one or more instances inside parent)
- – - – BLSE based content

- Document (once)
- – Part (one or more instances inside parent)
- – - Art (one or more instances inside parent)
- – - – Sect (one or more instances inside parent)
- – - – - Div (one or more instances inside parent)
- – - – - – BLSE based content

- Document (once)
- – Part (one or more instances inside parent)
- – - Art (one or more instances inside parent)
- – - – BLSE based content

- Document (once)
- – Part (one or more instances inside parent)

- – - BLSE based content

- Document (once)
- – Art (one or more instances inside parent)

- – - BLSE based content

- Document (once)
- – Sect (one or more instances inside parent)

- – - BLSE based content

- Document (once)
- – Div (one or more instances inside parent)
- – - BLSE based content