# Core MIDI Enumerations ## Topics ### Enumerations [`var kMIDIInvalidUniqueID: MIDIUniqueID`](/documentation/CoreMIDI/kMIDIInvalidUniqueID) An invalid identifier. [`struct MIDICICategoryOptions`](/documentation/CoreMIDI/MIDICICategoryOptions) [`enum MIDICIDeviceType`](/documentation/CoreMIDI/MIDICIDeviceType) [`enum MIDICIManagementMessageType`](/documentation/CoreMIDI/MIDICIManagementMessageType) [`enum MIDICIProcessInquiryMessageType`](/documentation/CoreMIDI/MIDICIProcessInquiryMessageType) [`enum MIDICIProfileMessageType`](/documentation/CoreMIDI/MIDICIProfileMessageType) [`enum MIDICIProfileType`](/documentation/CoreMIDI/MIDICIProfileType) [`enum MIDICIPropertyExchangeMessageType`](/documentation/CoreMIDI/MIDICIPropertyExchangeMessageType) [`enum MIDINetworkConnectionPolicy`](/documentation/CoreMIDI/MIDINetworkConnectionPolicy) [`enum MIDINoteAttribute`](/documentation/CoreMIDI/MIDINoteAttribute) [`struct MIDIPerNoteManagementOptions`](/documentation/CoreMIDI/MIDIPerNoteManagementOptions) [`struct MIDIProgramChangeOptions`](/documentation/CoreMIDI/MIDIProgramChangeOptions) [`enum MIDIUMPCIObjectBackingType`](/documentation/CoreMIDI/MIDIUMPCIObjectBackingType) [`enum MIDIUMPFunctionBlockDirection`](/documentation/CoreMIDI/MIDIUMPFunctionBlockDirection) [`enum MIDIUMPFunctionBlockMIDI1Info`](/documentation/CoreMIDI/MIDIUMPFunctionBlockMIDI1Info) [`enum MIDIUMPFunctionBlockUIHint`](/documentation/CoreMIDI/MIDIUMPFunctionBlockUIHint) [`struct MIDIUMPProtocolOptions`](/documentation/CoreMIDI/MIDIUMPProtocolOptions) [`enum MIDIUtilityStatus`](/documentation/CoreMIDI/MIDIUtilityStatus) [`enum UMPStreamMessageFormat`](/documentation/CoreMIDI/UMPStreamMessageFormat) [`enum UMPStreamMessageStatus`](/documentation/CoreMIDI/UMPStreamMessageStatus) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)