I've never really been able to wrap my mind around how "playlists" function with the "library" in iTunes.
Simply put for now, if I do an iVolume check or change in a playlist, does it make the change in the library?

I know changing ratings or titles does not affect the item in the library?

huck

There is only one song file linked to the same entry in both the Library and the Playlist, so yes, changes to tags on songs in playlists will affect their entry in the Library. I hope that makes sense.