typedef struct _ETW_GUID_ENTRY
{
     LIST_ENTRY GuidList;
     LONG RefCount;
     GUID Guid;
     LIST_ENTRY RegListHead;
     PVOID SecurityDescriptor;
     TRACE_ENABLE_CONTEXT LegacyEnableContext;
     ULONG LegacyProviderEnabled;
     TRACE_ENABLE_INFO ProviderEnableInfo;
     TRACE_ENABLE_INFO EnableInfo[8];
} ETW_GUID_ENTRY, *PETW_GUID_ENTRY;

Windows Vista Kernel Structures