typedef struct _WNODE_HEADER
{
     ULONG BufferSize;
     ULONG ProviderId;
     union
     {
          UINT64 HistoricalContext;
          struct
          {
               ULONG Version;
               ULONG Linkage;
          };
     };
     union
     {
          ULONG CountLost;
          PVOID KernelHandle;
          LARGE_INTEGER TimeStamp;
     };
     GUID Guid;
     ULONG ClientContext;
     ULONG Flags;
} WNODE_HEADER, *PWNODE_HEADER;

Windows Vista Kernel Structures