typedef struct _PO_DEVICE_NOTIFY
{
     LIST_ENTRY Link;
     PDEVICE_OBJECT TargetDevice;
     UCHAR OrderLevel;
     PDEVICE_OBJECT DeviceObject;
     WORD * DeviceName;
     WORD * DriverName;
     ULONG ChildCount;
     ULONG ActiveChild;
} PO_DEVICE_NOTIFY, *PPO_DEVICE_NOTIFY;

Windows Vista Kernel Structures