A sheet of notated music that comprises the essential elements of a song. The notation would include the melody line, chord progression, and often lyrics. These elements have everything that a chordophone (such as a piano or guitar) needs to perform the song alone or as an accompaniment for a combo. The notation also allows solo instruments (such as a trumpet, alto or tenor saxophone, trombone, or voice) to perform along with the chordophone. Many combos employ a full rhythm section that would also include a double bass and a drum kit.