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# NSWhoseSpecifier.SubelementIdentifier

`NSWhoseSpecifier` uses these constants to specify sub-elements within the collection of objects being tested that pass the specifier’s test.

```
enum SubelementIdentifier
```

## Overview

These constants are used by [`startSubelementIdentifier`](/documentation/Foundation/NSWhoseSpecifier/startSubelementIdentifier), [`startSubelementIdentifier`](/documentation/Foundation/NSWhoseSpecifier/startSubelementIdentifier), [`endSubelementIdentifier`](/documentation/Foundation/NSWhoseSpecifier/endSubelementIdentifier), and [`endSubelementIdentifier`](/documentation/Foundation/NSWhoseSpecifier/endSubelementIdentifier).

## Topics

### Constants

[`NSWhoseSpecifier.SubelementIdentifier.indexSubelement`](/documentation/Foundation/NSWhoseSpecifier/SubelementIdentifier/indexSubelement)

An element at a given index that meets the specifier test.

[`NSWhoseSpecifier.SubelementIdentifier.everySubelement`](/documentation/Foundation/NSWhoseSpecifier/SubelementIdentifier/everySubelement)

Every element that meets the specifier test.

[`NSWhoseSpecifier.SubelementIdentifier.middleSubelement`](/documentation/Foundation/NSWhoseSpecifier/SubelementIdentifier/middleSubelement)

The middle element that meets the specifier test.

[`NSWhoseSpecifier.SubelementIdentifier.randomSubelement`](/documentation/Foundation/NSWhoseSpecifier/SubelementIdentifier/randomSubelement)

Any element that meets the specifier test.

[`NSWhoseSpecifier.SubelementIdentifier.noSubelement`](/documentation/Foundation/NSWhoseSpecifier/SubelementIdentifier/noSubelement)

No sub-element met the specifier test. Valid only for specifying the end sub-element.; that is, there is no end, so consider all elements.


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