Copying from one field to another

I've learned a lot about mp3tag in the last week and I've figured out more things myself but one thing that eludes me is the ability to duplicate information to multiple fields.

Here's the issue at hand:
I've recently discovered a possible error with the way winamp or FLAC tags work (but that's not really my point).

I've been adding the %BAND% tag to all my various artists albums with great success but the FLAC files I have are not getting sorted properly within winamp. The %BAND% field exists within the files but winamp doesn't read it. I tried using %ALBUMARTIST% instead and that works fine. Now I desire a simple way to duplicate the info from %BAND% into the %ALBUMARTIST% field.

I've seen a few examples of regexp that swaps info in fields but I cannot understand the regexp syntax and therefore have had no success in modifying the strings for my needs. Is regexp the only solution or do other options exist?

Thank you.

A simple Format value action is the best solution here.

Thank you. Don't I feel embarrassed.