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# tag(at:unit:scheme:tokenRange:)

Returns a tag for a single scheme, for a given linguistic unit, at the specified character position.

```
func tag(at charIndex: Int, unit: NSLinguisticTaggerUnit, scheme: NSLinguisticTagScheme, tokenRange: NSRangePointer?) -> NSLinguisticTag?
```

## Parameters

`charIndex`

The position of the initial character.

`unit`

The linguistic unit. See [`NSLinguisticTaggerUnit`](/documentation/Foundation/NSLinguisticTaggerUnit) for possible values.

`scheme`

The tag scheme. See [`NSLinguisticTagScheme`](/documentation/Foundation/NSLinguisticTagScheme) for possible values.

`tokenRange`

A pointer to the token range.

## Return Value

Returns the tag for the requested tag scheme and linguistic unit, or `nil`. If a tag is returned, this function returns by reference the range of the token to `tokenRange`.

## Discussion

---

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