FILE_OBJECTID_INFORMATION - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers
#ifndef _NTIOAPI_H

typedef struct _FILE_OBJECTID_INFORMATION
{
    LONGLONG FileReference;
    UCHAR ObjectId[16]; // GUID
    union
    {
        struct
        {
            UCHAR BirthVolumeId[16];
            UCHAR BirthObjectId[16];
            UCHAR DomainId[16];
        };
        UCHAR ExtendedInfo[48];
    };
} FILE_OBJECTID_INFORMATION, *PFILE_OBJECTID_INFORMATION;

#endif

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This structure is documented in Windows Driver Kit.