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# MIDIEntityRef

An entity that a device owns and that contains endpoints.

```
typealias MIDIEntityRef = MIDIObjectRef
```

## Discussion

An entity object derives from [`MIDIObjectRef`](/documentation/CoreMIDI/MIDIObjectRef), and its owning object is a [`MIDIDeviceRef`](/documentation/CoreMIDI/MIDIDeviceRef).

Devices may have multiple logically distinct subcomponents; for example, a MIDI synthesizer and a pair of MIDI ports are addressable using a USB port. By grouping a device’s endpoints into entities, the system has enough information for an app to make reasonable assumptions about how to communicate bidirectionally with each entity, as required by MIDI librarian apps.

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