Swap tag fields

I want to swap tag fields (e.g. composer for ensemble) accross a batch of files. I am relatively new to MP3tag and cannot work out how to do it! I chose MP3tag for its versatility and ability to use expressions but I need a little more specific help than the manual gives to get going. :flushed: Any tips welcome!

The FAQs are there for a reason: Actions :rolleyes: