Edited version with temporary effects and placeholders — used for screenings, feedback rounds, and editing iterations. Never final quality.
You assemble the first rough cut, overlay music, add some quick-and-dirty effects — and need the whole thing ready to show tomorrow. That's your working copy. A film in a stage between raw material and final delivery, which circulates internally to gather feedback, validate editing decisions, or show the producer/director where you currently stand.
The working copy is not the final product. It lives on compromises: VFX are previsualizations or sketched placeholders. The sound is a stereo mix from the editing suite and proxy files. Color correction? At most, initial light passes with LUTs from the timeline engine. The edit itself can be completely reassembled in a few days — and often will be. This version needs to be created quickly, run on modest computers, and be agile.
On set or during dailies review, you need working copies to check pacing, see if cuts work, or if a scene fits dramatically. In feedback screenings, you show a working copy: the producer, director, perhaps the broadcaster or distributor see how the film "feels" without you having invested 6 weeks in sound design and color grading. During the editing phase, dozens of working copies are created, each with changes, each with a date and version. (This is also why you need version control — Version_151221_Edit-v3_with_new_music, not just "Edit_new.mov".)
The technical reality: Working copies are in low resolutions (1080p instead of 4K), with compressed codecs, often on SSDs for fast data transfers. You bounce audio tracks down, eliminate offline effects, use proxy material. The editing workstation runs smoothly. Creating a working copy is an art in itself — fast enough to distribute, but precise enough that the visual and timing decisions remain recognizable. Often they are still Quicktime files or DNxHD wrappers that play on any computer without proprietary software being necessary.
Only when you are finished with working copies — when the edit, timing, and structure are final — does the file go into online editing or DCP mastering. That's where the real quality happens: original material in full resolution, professional sound mix, final color correction.