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# CFTimeZoneResetSystem()

Clears the previously determined system time zone, if any.

```
func CFTimeZoneResetSystem()
```

## Discussion

If the default time zone is set to the same value as the system time zone or has not been explicitly set, this function clears it as well.

Subsequent calls to [`CFTimeZoneCopySystem()`](/documentation/CoreFoundation/CFTimeZoneCopySystem()) will attempt to re-determine the system time zone.

---

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