The extra tags represent extra information extracted or generated by ExifTool that is not directly associated with another tag group. The Group column lists the family 1 group name when reading. Tags with a "-" in this column are write-only.
Tags in the family 1 "System" group are referred to as "pseudo" tags because they don't represent real metadata in the file. Instead, this information is stored in the directory structure of the filesystem. The four writable "pseudo" tags (FileName, Directory, FileModifyDate and FileCreateDate) may be written without modifying the file itself.
Tag Name Writable Group Values / Notes Adobe Y! Adobe (the JPEG APP14 Adobe segment. Extracted only if specified. See the JPEG Adobe Tags for more information) CanonVRD Y! CanonVRD (the full Canon DPP VRD trailer block) Comment Y File (comment embedded in JPEG, GIF89a or PPM/PGM/PBM image) CurrentIPTCDigest N File (MD5 digest of existing IPTC data. All zeros if IPTC exists but Digest::MD5 is not installed. Only calculated for IPTC in the standard location as specified by the MWG. ExifTool automates the handling of this tag in the MWG module -- see the MWG Composite Tags for details) Directory Y! System (may be written to move the file to a specified directory. New directories are created as necessary) EXIF Y! EXIF (the full EXIF data block from JPEG, PNG, JP2, MIE and MIFF images) Error N ExifTool ExifByteOrder Y File (represents the byte order of EXIF information. May be written to set the byte order only for newly created EXIF segments)
'II' = Little-endian (Intel, II)
'MM' = Big-endian (Motorola, MM)
ExifToolVersion N ExifTool ExifUnicodeByteOrder Y - (specifies the byte order to use when writing EXIF Unicode text. The EXIF specification is particularly vague about this byte ordering, and different applications use different conventions. By default ExifTool writes Unicode text in EXIF byte order, but this write-only tag may be used to force a specific order)
'II' = Little-endian (Intel, II)
'MM' = Big-endian (Motorola, MM)
FileAccessDate N System (the date/time of last access of the file. Note that this access time is updated whenever any software, including ExifTool, reads the file) FileCreateDate Y! System (the filesystem creation date/time. Windows only. Requires Win32API::File::Time for writing. Note that although ExifTool can not currently access the filesystem creation time on other systems, the creation time is pushed backwards on OS X by writing an earlier modification time, which provides a mechanism to write this indirectly: 1) Rewrite the file to set the filesystem creation and modification times to the current time, 2) Set FileModifyDate to the desired creation time, then 3) Restore FileModifyDate to its original value) FileInodeChangeDate N System (the date/time when the file's directory information was last changed. Non-Windows systems only) FileModifyDate Y! System (the filesystem modification date/time. Note that ExifTool may not be able to handle filesystem dates before 1970 depending on the limitations of the system's standard libraries) FileName Y! System (may be written with a full path name to set FileName and Directory in one operation. See filename.html for more information on writing the FileName and Directory tags) FilePermissions N System (r=read, w=write and x=execute permissions for the file owner, group and others. The ValueConv value is an octal number so bit test operations on this value should be done in octal, ie. 'oct($filePermissions#) & 0200') FileSequence N ExifTool (sequence number for each processed file when extracting or copying information, beginning at 0 for the first file. Not generated unless specifically requested) FileSize N System (note that the print conversion for this tag uses historic prefixes: 1 kB = 1024 bytes, etc.) FileType N File Geosync Y - (this write-only tag specifies a time difference to add to Geotime for synchronization with the GPS clock. For example, set this to "-12" if the camera clock is 12 seconds faster than GPS time. Input format is "[+-][[[DD ]HH:]MM:]SS[.ss]". Must be set before Geotime to be effective. Additional features allow calculation of time differences and time drifts, and extraction of synchronization times from image files. See the geotagging documentation for details) Geotag Y - (this write-only tag is used to define the GPS track log data or track log file name. Currently supported track log formats are GPX, NMEA RMC/GGA/GLL, KML, IGC, Garmin XML and TCX, Magellan PMGNTRK, Honeywell PTNTHPR, and Winplus Beacon text files. See geotag.html for details) Geotime Y - (this write-only tag is used to define a date/time for interpolating a position in the GPS track specified by the Geotag tag. Writing this tag causes GPS information to be written into the EXIF or XMP of the target files. The local system timezone is assumed if the date/time value does not contain a timezone. May be deleted to delete associated GPS tags. A group name of 'EXIF' or 'XMP' may be specified to write or delete only EXIF or XMP GPS tags. The Geotag tag must be assigned before this tag) ICC_Profile Y! ICC_Profile (the full ICC_Profile data block) ID3Size N File IPTC Y! IPTC (the full IPTC data block) ImageHeight N File ImageWidth N File JPEGDigest N File (an MD5 digest of the JPEG quantization tables is combined with the component sub-sampling values to generate the value of this tag. The result is compared to known values in an attempt to deduce the originating software based only on the JPEG image data. For performance reasons, this tag is generated only if specifically requested) MIMEType N File MaxVal N File NewGUID N ExifTool (generates a new, random GUID with format YYYYmmdd-HHMM-SSNN-PPPP-RRRRRRRRRRRR, where Y=year, m=month, d=day, H=hour, M=minute, S=second, N=file sequence number in hex, P=process ID in hex, and R=random hex number; without dashes with the -n option. Not generated unless specifically requested) Now N ExifTool (the current date/time. Useful when setting the tag values, ie.
"-modifydate<now". Not generated unless specifically requested)
PreviewImage Y File PreviewPNG N File PreviewWMF N File RAFVersion N File ResourceForkSize N System (size of the file's resource fork if it contains data. Mac OS only. If this tag is generated the ExtractEmbedded option may be used to extract resource-fork information as a sub-document. When writing, the resource fork is preserved by default, but it may be deleted with
-rsrc:all=on the command line)
Warning N ExifTool XMP Y! XMP (the full XMP data block) XResolution N File YResolution N File
<-- ExifTool Tag Names