IIRC films used to be edited by manually splicing the master _physical_ film. This altered the original master copy. The development of non-linear video editing revolutionized the industry, starting with Avid and proceeding to the Amiga toaster and now to the marvels of magic that we can literally carry in our phones.

While it would be possible to edit a film using the original camera reel, this is generally not a good idea because (1) most motion pictures are captured on negative film and (2) the repeated cuts, splices, and general handling of the film that happens during edit will inevitably damage it.

The solution to both problems is to produce a workprint from the camera negative and edit with that. This inverts the negative image and gives you a copy that you can play with freely.

Watching someone editing on a Steenbeck [0], you will quickly see the importance of not editing the camera negative directly.

Once the edit decisions are finalized, the original camera negative is carefully cut and spliced to match the workprint, and a pristine "answer print" is struck from the edited camera negative. Traditionally, this is also where color timing is done—the printer lights can be configured to balance different shots and scenes as the answer print is being made.

The final release prints are usually third-generation copies (if you don't count the camera negative as a copy)—(1) a handful of interpositives are made from the original camera negative following the exact procedure used to make the answer print, then (2) internegatives are struck from the interpositives, and (3) a large number of release prints can be struck from the internegatives.

A notable exception to this was the release of Dunkirk (2017). The 37 IMAX screens in the world [1] that were exhibiting a 15-perf 70mm film print were actually showing a first-generation copy struck directly from the original camera negative.

(All that said, it is possible to shoot on reversal film, which is positive out of the camera, and can be edited and projected directly. Also, I've never edited a film like this myself and likely got a few things wrong—so take this with a grain of salt.)

[0] https://www.youtube.com/watch?v=dUxbfiZ_-9Y [1] https://www.gizmodo.com.au/2017/07/imax-melbourne-is-the-onl...

> it is possible to shoot on reversal film, which is positive out of the camera, and can be edited and projected directly. Also, I've never edited a film like this myself

I took a film production class in which we shot and edited negativeless 16mm film. Tape held together the splices when they were screened the day after editing, never had a problem. 25+ years later, my guess is they’d fall apart if you tried to project them. I didn’t pay to get a VHS transfer made then so they’ll probably never be seen again; no great loss.

Editing film was very much non-linear editing to being with. The transition to tape based editing meant that you were limited to managed edits from source decks to a destination tape deck.

That too, but non-linear means that you are working with random access files, basically. Linear editing systems were typically tape based. You'd then have to access the footage in a linear fashion. Typically you had 2 or 3 input tape decks and one output tape deck. This existed both for analog and digital tapes with more or less advanced software support to access the tapes.

For people who work in the TV industry there's still good reasons to differentiate. TV news is still edited using linear editing in a lot of small local stations (because it's fast and cheap).

It's a standard term of art in video editing.

All of this has happened before: https://youtu.be/x3l7CpnpyGw

Maybe they meant non-destructive

This is a standard term in video production, despite the fact that the parent never heard of it.