In each style of music, there are different musical approaches and styles that rhythm section members are expected to use. For example, in a country music song, the guitarist will be expected to be able to perform a chord progression using an intricate fingerpicking style; in a heavy metal song, the guitarist will be expected to play power chords and complex, precise rhythmic patterns; in a jazz song, a guitarist will be expected to be able to play "jazz voicings" of the chords, which emphasize the third, seventh and often the sixth or ninth chord tones (this contrasts with the barre chord voicings used in pop and rock, which emphasize the root, fifth, and to a lesser degree, the third of the chord). Drummers and percussionists are expected to be able to improvise or prepare rhythm parts that suit the style of a given song. In some cases, an arranger, orchestrator or composer will provide a written-out bass part or drum part written in music notation (the five-line staff in which the notes are round symbols with or without stems). It is rare in jazz or rock for chords to be written out in music notation; the arranger or songwriter typically writes the chord symbol and expects the guitarist to improvise the appropriate chord voicing.