Nearly all soprano and piccolo clarinets have keywork enabling them to play the E below middle C as their lowest written note (in scientific pitch notation that sounds D3 on a soprano clarinet or C4, i.e. concert middle C, on a piccolo clarinet), though some B♭ clarinets go down to E♭3 to enable them to match the range of the A clarinet. On the B♭ soprano clarinet, the concert pitch of the lowest note is D3, a whole tone lower than the written pitch. Most alto and bass clarinets have an extra key to allow a (written) E♭3. Modern professional-quality bass clarinets generally have additional keywork to written C3. Among the less commonly encountered members of the clarinet family, contra-alto and contrabass clarinets may have keywork to written E♭3, D3, or C3;the basset clarinet and basset horn generally go to low C3. Defining the top end of a clarinet’s range is difficult, since many advanced players can produce notes well above the highest notes commonly found in method books. G6 is usually the highest note clarinetists encounter in classical repertoire. The C above that (C7 i.e. resting on the fifth ledger line above the treble staff) is attainable by advanced players and is shown on many fingering charts,and fingerings as high as G7 exist.