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# containerID

The container identifier, as found during the probe operation.

```
var containerID: FSContainerIdentifier? { get }
```

## Discussion

This value is non-`nil` unless the result is [`FSMatchResult.notRecognized`](/documentation/FSKit/FSMatchResult/notRecognized).
For formats that lack a durable UUID on which to base a container identifier — which is only legal for a [`FSUnaryFileSystem`](/documentation/FSKit/FSUnaryFileSystem) — this value may be a random UUID.

---

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