I'm having a hard time figuring out by the question.

Are you asking what happens if the first  index event doesn't have any child events?

In general, each paragraph will become its own kind 30041 zettel, so if there are no subsections, the document will be turned into a single index with a bunch of one-paragraph zettels.

Does that answer your question, or did I just misunderstand it? 

 What if it's only 

"Document metadata

=== This is a header"

And then it ends. Maybe because someone copy-pasted wrong or pushed the button too early. Or maybe they just want to create an index and update it later, with the relevant e tags.

Then it would only generate a 30040, right? Or would it return an error? Or would they need to confirm that it should only generate a 30040?