Autofill Fields

[ohrenkino]

@mconnolly

Or point me to a doc or something

What about the help? Here you find a description of the first steps.

First Steps – Mp3tag Documentation

And then perhaps the HowTo Section and the FAQs, perhaps on the problem to copy one field to another:

Actions and batch-operations

How to copy one field value to another field? Example how to copy the content of the ARTIST field to the ALBUMARTIST field: Create a new action in an existing action group or make a new action group. Action type: Format value Field: ALBUMARTIST Format string: %artist% Note: If you want to copy all possible values of a field (in case you have multiple artist fields), the internal scripting function $meta_sep can be used in the format string, e.g., $meta_sep(artist,\\\\)