Publishing is directly related to the “idea” of the song. Think of your last song that you released for example. Publishing is born when you write lyrics on a piece of paper or on your phone, or when you choose what snare to add in your song as well as the melodies to add. Those are all tied to your Publishing Rights - so anything that you “write” on your DAW the very first time. The idea is also commonly referred to as “Work” in the Publishing realm.