A Tag ID or Index is given in the first column of each table. A Tag ID is the computer-readable equivalent of a tag name, and is the identifier that is actually stored in the file. An Index refers to the location of the information, and is used if the information is stored at a fixed position in a data block.
A Tag Name is the handle by which the information is accessed. In some instances, more than one name may correspond to a single tag ID. In these cases, the actual name used depends on the context in which the information is found. Case is not significant for tag names. A question mark after a tag name indicates that the information is either not understood or not verified -- these tags are not extracted by ExifTool unless the Unknown (-u) option is enabled.
The Writable column indicates whether the tag is writable by ExifTool. Anything but an "N" in this column means the tag is writable. A "Y" indicates writable information that is either unformatted or written using the existing format. Other expressions give details about the information format, and vary depending on the general type of information. The format name may be followed by a number in square brackets to indicate the number of values written, or the number of characters in a fixed-length string (including a null terminator which is added if required).
An asterisk (*
) in the Writable column indicates a 'protected' tag
which is not writable directly, but is set via a Composite tag. A tilde
(~
) indicates a tag this is only writable when print conversion is
disabled (by setting PrintConv to 0, or using the -n option). An
exclamation point (!
) indicates a tag that is considered unsafe to write
under normal circumstances. These 'unsafe' tags are not set when calling
SetNewValuesFromFile() or when using the exiftool -AllTagsFromFile option,
and care should be taken when editing them manually since they may affect
the way an image is rendered.
The HTML version of this document also lists possible Values for all tags which have a discrete set of values, or gives Notes for some tags.
Note: If you are familiar with common meta-information tag names, you may
find that some ExifTool tag names are different than expected. The usual
reason for this is to make the tag names more consistent across different
types of meta information. To determine a tag name, either consult this
documentation or run exiftool -S
on a file containing the information in
question.