Insert of words, lines, paragraphs.

[Anton]

Those considerations should be combined with our knowledge of labels. Inter-dependent labels within a folio is some thing that adds extreme complexity. So it's reasonable to assume that labels are not mutually dependent.

So: labels encoded in a single pass and text encoded in multiple passes.

Actually interleaving is the first and simplest thing that comes to mind.

Now: can any "pass patterns" be visually identified?

Mind that the text should be decodable - that's, either there is a fixed structure comprehensible without any special tokens or there are some tokens spread over the text.