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# FSExtentType.data

An extent type to indicate valid data.

```
case data
```

## Discussion

Use this type for all extents on a file system that doesn’t support sparse files.

> Tip: The kernel keeps track of the end of file, so it knows a range of `[EOF, allocated space]` is uninitialized. Because of this behavior, it’s valid to pass the data extent type for such a range.

---

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