# DOCX Level 4-6 and Round-trip Preserve Foundation

## Level 4

Comments, footnotes, header/footer and hyperlink metadata are imported/exported through OOXML parts where the current model supports them.

## Level 5

High-fidelity constructs such as floating images, text boxes, shapes, charts, equations and complex section layouts are treated as explicit preserve/placeholder candidates.  The editor should not silently flatten them into plain paragraphs.

## Level 6

Unknown OOXML package data is stored in UWPSX under `ooxml/preserved-parts.json`, with policy metadata in `ooxml/roundtrip-policy.json`.  Future export versions can restore or upgrade preserved parts without losing original package context.