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# layerUUID

A UUID of the image that the framework uses to validate its compatibility with the layer above it in the stack

```
var layerUUID: UUID? { get }
```

## Discussion

All images contain a layer UUID, except for RAW images.

The layer UUID changes when the framework first writes to an image. In a stacked disk image, the framework
can only write to the topmost image. The layer UUID of cache layers never changes.

---

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