How do Music.app and ID3 differ regarding copyright notice?

How does Music.app find and display a copyright notice in the File tab of songs? If I open a purchased track and an edited MP3 in Amadeus Pro , it shows the copyright notice for both as "Copyright Notice" in its "Additional" tab. But in Music’s Info pane, it only appears for the Purchased file. eyeD3 does not show it for either song file. exiftool shows it for both with a tag name of "Copyright" I have more than half of an audio editing task automated, and I'd like to script adding the copyright notice, instead of pasting it in manually.  exiftool can’t write to MP3 files, and eyeD3 doesn't have copyright in its options.  I’d also like to have Music.app display the notice for all files.