## Extra Tags

The extra tags represent extra information extracted or generated by ExifTool that is not directly associated with another tag group. The three writable "pseudo" tags (FileName, Directory and FileModifyDate) may be written without the need to rewrite the file since their values are not contained within the file data. These "pseudo" tags belong to the family 1 "System" group.

> Tag Name | Writable | Values / Notes
> --- | --- | ---
> CanonVRD | Y! | (the full Canon DPP VRD trailer block)
> Comment | Y | (comment embedded in JPEG, GIF89a or PPM/PGM/PBM image)
> CurrentIPTCDigest | N | (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)
> Directory | Y! |
> EXIF | Y! | (the full EXIF data block from JPEG, PNG, JP2, MIE and MIFF images)
> Error | N |
> ExifByteOrder | Y | (only writable for newly created EXIF segments) 'II' = Little-endian (Intel, II) 'MM' = Big-endian (Motorola, MM)
> ExifToolVersion | N |
> ExifUnicodeByteOrder | Y | (the EXIF specification is particularly vague about the byte ordering for Unicode text, 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 byte order) 'II' = Little-endian (Intel, II) 'MM' = Big-endian (Motorola, MM)
> FileModifyDate | Y! | (the filesystem modification time)
> FileName | Y! | (may be written with a full path name to set FileName and Directory in one operation)
> FilePermissions | N | (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")
> FileSize | N |
> FileType | N |
> 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, and Magellan PMGNTRK)
> 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 the following 8 tags to be written: GPSLatitude, GPSLatitudeRef, GPSLongitude, GPSLongitudeRef, GPSAltitude, GPSAltitudeRef, GPSDateStamp and GPSTimeStamp. 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 value of Geotag must be assigned before this tag)
> ICC_Profile | Y! | (the full ICC_Profile data block)
> ID3Size | N |
> ImageHeight | N |
> ImageWidth | N |
> JPEGDigest | N | (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 |
> MaxVal | N |
> Now | N | (the current date/time. Useful when setting the tag values, ie. `"-modifydate<now"`. Not generated unless specifically requested)
> PreviewImage | Y |
> PreviewPNG | N |
> RAFVersion | N |
> ResourceForkSize | N | ([Mac OS only] size of the file's resource fork if it contains data. If this tag is generated the ExtractEmbedded option may be used to extract resource-fork information as a sub-document)
> Warning | N |
> XMP | Y! | (the full XMP data block)
> XResolution | N |
> YResolution | N |

(This document generated automatically by Image::ExifTool::BuildTagLookup)
Last revised Oct 22, 2010

<-- ExifTool Tag Names