C# Definition:

  [StructLayout(LayoutKind.Sequential)]
  struct SP_DEVICE_INTERFACE_DATA
  {
    public  Int32    cbSize;
    public  Guid     interfaceClassGuid;
    public  Int32    flags;
    private UIntPtr  reserved;
  }

Members:

cbSize

Size of the structure, in bytes.

interfaceClassGuid

GUID of the device interface class.

flags

One of the SPINT_ values.

reserved

Reserved; do not use.

Notes:

Used with SetupDiEnumDeviceInterfaces and SetupDiGetDeviceInterfaceDetail