Here you can configure Custom Field Values per tag field. They are available as entries in the Tag Panel’s drop-down lists or as auto-complete options when editing in place in the File List or via Extended Tags. This helps maintain consistency, for example, by defining a list of genres, composer names, countries, or languages.

It’s still possible to only see the values of the selected files if you prefer that, but an empty field on the Tag Panel offers the custom values (if set) from the drop-down list.

The Genre field has a dedicated option to Show only user-defined genres. If enabled, the drop-down list of the Genre field on the Tag Panel only shows user-defined genres after a restart of Mp3tag. Note that these genres are not saved to an ID3v1 tag due to the limitations of the tag format.

Custom Field Values can also be imported from a text file, where each line denotes one value. Exporting the lists allows for creating backups or sharing custom list values.

For quick addition you can use Shift+Enter when editing in the Tag Panel, which adds the contents of the current Tag Panel field to the list of custom field values for that field.