---
title: IOUSBDescriptorHeader
framework: IOKit
role: symbol
role_heading: Structure
platforms: [Mac Catalyst 13.0+, macOS 10.0+]
path: iokit/iousbdescriptorheader
---

# IOUSBDescriptorHeader

## Declaration

```occ
typedef struct IOUSBDescriptorHeader {
    ...
} IOUSBDescriptorHeader;
```

## Overview

Overview Standard header used for all USB descriptors. Used to read the length of a descriptor so that we can allocate storage for the whole descriptor later on.

## Topics

### Instance Properties

- [bDescriptorType](iokit/iousbdescriptorheader/1425797-bdescriptortype.md)
- [bLength](iokit/iousbdescriptorheader/1425367-blength.md)

## See Also

### Related Documentation

- [IOUSBDescriptorHeader](iokit/usb_h_user-space/iousbdescriptorheader.md)