#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;
View code on GitHubThis structure is documented in Windows Driver Kit.