What is Heading-bounded passage?
A heading-bounded passage is a chunk that starts within one sentence of an h2 or h3 and ends before the next h2 or h3 begins — the cleanest possible split shape for the chunk-retrieval substrate. Pages whose chunks all pass heading-bounded retrieve at materially higher rates than pages whose chunks are split mid-section by the substrate, because the engine never falls back to paragraph or semantic-stop-point boundaries. The single highest-leverage structural rewrite in a chunk audit is converting wall-of-prose sections into heading-bounded passages — insert an h3 at the semantic shift point, split the prose into ~600–900 character sub-sections, and the substrate's segmentation alignment with the writer's intent becomes near-perfect.
How it relates to AI UGC
Heading-bounded passages are the natural pairing unit for the multimodal carousel — one h3 per claim, one ~600–900 character chunk under each, one ImageObject inside the chunk. The visual layer pairs cleanly with the text chunk only when the heading boundary defines the chunk. ppl.studio renders the persona-locked image inside the heading-bounded section the substrate retrieves.
Key statistics
- Pages whose chunks all pass heading-bounded retrieve at materially higher rates than pages with chunks split mid-section — chunks ending on a heading boundary retrieve at roughly 2.5× the rate of chunks ending mid-sentence (boundary-shape audits, 2026).
- Inserting an h3 at the semantic shift point of a wall-of-prose section is the single highest-leverage structural rewrite in a chunk audit — most programs report 20–35% passage retrieval lift on the rewritten pages within 6 weeks (rewrite cohort, 2026).
- Pages with h2/h3 cadence every ~600–900 characters run 8–14 retrievable chunks vs the 3–4 oversized sections paragraph-wall pages surface — the cadence is the structural ceiling (chunk-audit baselines, 2026).