[pfisherman]

Thanks for the technical explanation! This is pretty fascinating.

So it works kind of like a soft delete — dereference instead of scrubbing the bits.

Is this behavior generally explicitly defined in PDF editors (i.e. an intended feature)? Is it defined in some standard or set of best practices? Or is it a hack (or half baked feature) someone implemented years ago that has just kind of stuck around and propagated?

[clord]

The intention is to make editing easy and quick on slow and memory deficient computers. This is how for example editing a pdf with form field values can be so fast. It’s just appending new values for those nodes. If you need to omit edits you’d have to regenerate a fresh pdf from the root.