C# Constants:

    const uint IOCTL_DISK_GET_DRIVE_LAYOUT_EX = 0x00070050;

Alternative C# Constants:

    private const uint FILE_DEVICE_DISK = 0x00000007;
    private const uint IOCTL_DISK_BASE = FILE_DEVICE_DISK;
    private const uint METHOD_BUFFERED = 0;
    private const uint FILE_ANY_ACCESS = 0;

    private static readonly uint IOCTL_DISK_GET_DRIVE_LAYOUT_EX = CtlCode(IOCTL_DISK_BASE, 0x0014, METHOD_BUFFERED, FILE_ANY_ACCESS);

    private static uint CtlCode(uint deviceType, uint function, uint method, uint access)
    {
          return ((deviceType) << 16) | ((access) << 14) | ((function) << 2) | (method);
    }

VB Constants:

TODO

Notes:

C++ Header file: WinIoCtl.h