Upon doing a bit of research, the answer to my question is:  artist, album, and album artist ("artist" being song artist).  Slightly different for compilations (I think it ignores the artist fields, but don't know if it ignores both).  A frequent point on doing this research is to watch out for invisible characters.  So I would say:  add some invisible characters.  Try putting a space on the end or something.  Let us know how it works, I'm booted into linux right now, so can't try it -- I usually only boot up into Windows for iTunes once a week on weekends.