The FILE_INFO_2 structure contains the identifier for a file, device, or pipe.

 typedef struct _FILE_INFO_2 {
   DWORD fi2_id;
 } FILE_INFO_2,
  *PFILE_INFO_2,
  *LPFILE_INFO_2;

fi2_id: Specifies a DWORD value that contains the identifier that is assigned to the file, device, or pipe when it was opened. See section 3.1.1 for details.