typedef struct _PLUGPLAY_EVENT_BLOCK
{
     GUID EventGuid;
     PLUGPLAY_EVENT_CATEGORY EventCategory;
     ULONG * Result;
     ULONG Flags;
     ULONG TotalSize;
     PVOID DeviceObject;
     ULONG u;
} PLUGPLAY_EVENT_BLOCK, *PPLUGPLAY_EVENT_BLOCK;

Windows Vista Kernel Structures