High precision modification time. If this option is disabled, file modification time is stored with two seconds precision. It is enough for FAT file system, but insufficient for NTFS. Enabling this option may slightly increase the backup size, up to 5 bytes per each archived file, but it allows WinRar to preserve the file time with 0.0000001 second precision. WinRar automatically turns off the high precision mode if the capability is not supported by the source file system, so it will not be active when backing up from FAT disks.
Store creation time. Store last access time. Windows file systems keep three different time fields with each file: last modification, creation and last access time. By default WinRar stores only the last modification time, but using this option you may enable storing of additional information. It may be useful for backups.