> For the complete documentation index, see [llms.txt](https://docs.unitlab.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.unitlab.ai/documentation/releases/release-splits-and-grouped-data.md).

# Release splits and grouped data

Split policy is a modeling and provenance decision. Related views, sequences, documents, patients, acquisitions, or Data Groups may need to remain in one split to prevent leakage.

A release is a versioned annotation snapshot with:

* visibility such as Private or Public;
* modality;
* version number;
* creation date;
* item counts;
* data preview;
* annotation preview;
* Clone Release;
* Overview, Data, and Settings tabs;
* item type, data ID, preview, ground truth, and metadata.

A release can contain video, document, and audio items together. Metadata is represented as structured content: video metadata can include frame, video, and audio facts, while document metadata includes PDF and page information.

### Use this in production

* Choose the split unit before choosing percentages.
* Keep related Data Group members, study series, time-adjacent sequences, or same-entity samples together when required.
* Record the random seed or deterministic membership rule when available.
* Inspect class, source, modality, and difficulty distribution across splits.
* Treat split changes as a new release version.