If no group name is specified, the tag is created in the preferred group, and updated in any other location where a same-named tag already exists.

TAG may contain one or more leading family 0, 1, 2 or 7 group names, prefixed by optional family numbers, and separated colons. ^= is used to write an empty string instead of deleting the tag when no VALUE is given, but otherwise it is equivalent to =, but note that the caret must be quoted on the Windows command line. += may also be used to increment numerical values (or decrement if VALUE is negative), and -= may be used to conditionally delete or replace a tag (see 'WRITING EXAMPLES' for examples). += and -= are used to add or remove existing entries from a list, or to shift date/time values (see Image::ExifTool:: and note 6 below for more details). comment=wow), or delete the tag if no VALUE is given (eg. Write a new value for the specified tag (eg. I confirm that worked as I tried to demonstrate above.Exiftool Application Documentation exiftool Application DocumentationĮxiftool - Read and write meta information in files SYNOPSIS ReadingĮxiftool FILE. You should be able to write the XMP-tiff:DateTime tag because this is standard (note that the description for this is 'Date/Time Modified', which may cause some confusion). If this is really only possible with a config file could you please be so kind to provide some minimum example which lets me either remove or change DateTime?

I guess the application I'm using (fgallery) has some fallback or is just confused by the duplicated tag names in different tag spaces. Its not that I would like to 'invent' something by myself and may be its even better if I would remove the tag at all if it is non-standard.

Why do I need to define a tag in a config file if it is existing in the image file that is to be processed. I admit I have some problem to understand the logic behind this. There is no standard XMP-exif tag called 'DateTime', so you would need to create a user-defined tag to be able to write this.

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