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# OSBundleUsageDescriptionKey

A message that tells the user why the app is trying to install a driver extension bundle.

```
let OSBundleUsageDescriptionKey: String
```

## Discussion

This key is required for all DriverKit extensions and must be in the extension’s `Info.plist` file. Failure to include this key results in an error at activation time. For system extensions that are not DriverKit extensions, use [`NSSystemExtensionUsageDescriptionKey`](/documentation/SystemExtensions/NSSystemExtensionUsageDescriptionKey) instead.

---

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