<!--
{
  "documentType" : "article",
  "framework" : "USBDriverKit",
  "identifier" : "/documentation/USBDriverKit/additional-specifications",
  "metadataVersion" : "0.1.0",
  "role" : "collectionGroup",
  "title" : "Additional Specifications"
}
-->

# Additional Specifications

Request information from a device and get hardware and timing information.

## Topics

### Device Requests

[Standard Device Requests](/documentation/USBDriverKit/standard_device_requests-enum)

Constants for the standard requests you can make to a USB device.

[`struct IOUSBDeviceRequest;`](/documentation/USBDriverKit/IOUSBDeviceRequest)

A structure that defines a standard device request.

[`struct IOUSBDeviceRequestSetSELData;`](/documentation/USBDriverKit/IOUSBDeviceRequestSetSELData)

The structure for receiving system exit latency values.

[`enum tIOUSBDeviceRequest : unsigned int;`](/documentation/USBDriverKit/tIOUSBDeviceRequest)

Constants for configuring a device request.

[`enum tIOUSBDeviceRequestTypeValue : unsigned int;`](/documentation/USBDriverKit/tIOUSBDeviceRequestTypeValue)

Constants indicating the type of request to make from a device.

[`enum tIOUSBDeviceRequestRecipientValue : unsigned int;`](/documentation/USBDriverKit/tIOUSBDeviceRequestRecipientValue)

Constants indicating the type of object that receives the results of a request.

[Get Status Options](/documentation/USBDriverKit/get_status_options-enum)

Constants for use with get status requests.

[Suspend Feature Options](/documentation/USBDriverKit/suspend_feature_options-enum)

Constants to use when enabling the suspend feature of a device.

[Link Power Management Capabilities](/documentation/USBDriverKit/link_power_management_capabiliti-enum)

Constants for link power management capabilities.

[Standard Feature Selectors](/documentation/USBDriverKit/standard_feature_selectors-enum)

Constants for the standard feature selectors.

### Hub Port Status Requests

[`struct IOUSB30HubPortStatusExt;`](/documentation/USBDriverKit/IOUSB30HubPortStatusExt)

The structure for getting the port status of a USB 3 hub.

[`enum tIOUSBDeviceRequestDirectionValue : unsigned int;`](/documentation/USBDriverKit/tIOUSBDeviceRequestDirectionValue)

Enumerated device request direction values.

[`enum tIOUSB30HubExtStatus : unsigned int;`](/documentation/USBDriverKit/tIOUSB30HubExtStatus)

Bit masks for getting port status values.

[`enum tIOUSB30HubPortStatusCode : unsigned int;`](/documentation/USBDriverKit/tIOUSB30HubPortStatusCode)

Constants for the port status type codes.

[Hub Parameters](/documentation/USBDriverKit/hub_parameters-enum)

Constants for hub parameters.

### Device Notifications

[`enum tIOUSB30DeviceNotificationType : unsigned int;`](/documentation/USBDriverKit/tIOUSB30DeviceNotificationType)

Constants indicating the type of a device notification.

### Electrical Characteristics

[`enum tIOUSB20BusCurrent : unsigned int;`](/documentation/USBDriverKit/tIOUSB20BusCurrent)

Constants for the available current levels for USB 2.0 devices.

[`enum tIOUSB30BusCurrent : unsigned int;`](/documentation/USBDriverKit/tIOUSB30BusCurrent)

Constants for the available power levels of USB 3.0 devices.

[`enum tIOUSBBusVoltage : unsigned int;`](/documentation/USBDriverKit/tIOUSBBusVoltage)

A constant for the USB bus voltage.

### Timing Parameters

[`enum tIOUSB30LinkStateTimeout : unsigned int;`](/documentation/USBDriverKit/tIOUSB30LinkStateTimeout)

Constants for the link state timeout values on USB 3.0 devices.

[`enum tIOUSB30ResetTimeout : unsigned int;`](/documentation/USBDriverKit/tIOUSB30ResetTimeout)

Constants for the reset timeout values on USB 3.0 devices.

[`enum tIOUSB30TimingParameters : unsigned int;`](/documentation/USBDriverKit/tIOUSB30TimingParameters)

Constants for USB 3.0 timing parameters.

[Timing Parameters](/documentation/USBDriverKit/timing_parameters-enum)

Constants for ping response times.


---

Copyright &copy; 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)