Legal or contractual rule allowing separate processing and archiving of image and sound — prevents technical or creative locking.
You know the problem: At some point in the edit, you realize the sound mix from the previous day was perfect—but the DP wants to do a color correction that locks the entire DCP package again. Or vice versa: The grading version is final, but the sound designer needs another three days for the immersive version. The uncoupled / no-sync rule is the production law answer to precisely these kinds of scenarios—it allows you to process, version, and archive picture and sound independently, without a change in one domain blocking the other.
Legally, this works through production contracts that explicitly state: Editing and color correction run parallel to sound post-production, not sequentially one after the other. This not only saves weeks but also prevents the classic scenario where the sound engineer has to wait until the last camera ID is corrected—or where the DI suite is blocked because master stems are still being mixed. You can create separate DCP versions: one with final picture grading and preliminary sound, one with final sound mix and frozen picture grade. Both versions remain independent in the archive.
In practice, this means: You need clear version numbers and robust metadata management. If picture and sound are not coupled, you must meticulously document which picture lock belongs to which sound stem. This is not a problem if you work with separate masters from the outset—but dangerous if you later have to try to merge them. Some studios work with synchronization only upon final export: Picture Master (finalized), Sound Master (finalized), then a separate encoding process for each delivery. This gives you maximum flexibility, but also costs you more timecode management and pre-mix planning.
The uncoupled / no-sync rule is particularly helpful for large international productions where picture grading happens in L.A., sound mix in Berlin, and archiving in Canada—all without mutual blocking. It is also the reason why you now see on-set DMR (Digital Intermediate Master Records) and separate export specifications for picture and sound. The decoupling from classic picture lock workflows is, not least, a response to streamer requirements that need multiple formats, languages, and versions simultaneously—and decoupling helps immensely here.