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# Selection Markers

The following constants are used to describe special cases for a controller’s selection.

## Topics

### Constants

[`var NSMultipleValuesMarker: AnyObject`](/documentation/AppKit/NSMultipleValuesMarker)

This marker indicates that a key’s value contains multiple values that differ.

[`var NSNoSelectionMarker: AnyObject`](/documentation/AppKit/NSNoSelectionMarker)

This marker indicates that the controller’s selection is currently empty.

[`var NSNotApplicableMarker: AnyObject`](/documentation/AppKit/NSNotApplicableMarker)

This marker indicates that an object is not key-value coding compliant for the requested key.


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