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, not verified, or not very useful -- these tags are not extracted by ExifTool unless the Unknown (-u) option is enabled. Be aware that some tag names are different than the descriptions printed out by default when extracting information with "exiftool". To see the tag names instead of the descriptions, use "exiftool -s".
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 (*
) after an entry 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).
A slash (/
) indicates an 'avoided' tag that is not created unless the
group is specified (due to name conflicts with other tags). 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 -TagsFromFile option
unless specified explicitly, and care should be taken when editing them
manually since they may affect the way an image is rendered. A plus sign
(+
) indicates a 'list' tag which supports multiple instances.
The HTML version of this document also lists possible Values for all tags which have a discrete set of values, and 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.
<-- Back to ExifTool Home Page