Optional content groups become layers (in paint order, shared by every page)
with their name, default visibility, print usage and lock; art outside them
goes to a layer per page. Art that is off isn't lost: an update appended to
the file drops its /OCProperties so the interpreter draws every group, and
the marked-content sequences found walking the content (checked by tag) route
the art to its group's layer, which comes in hidden. A form hidden by its own
/OC keeps the file as it is. document.open layers: false keeps one layer per
page of only what shows (Save then asks for a name).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>