   {name: 'Minor 7th', abbr: 'min7', pitch_classes: '037t'},
   {name: 'Dom 7 b5', abbr: '7b5', pitch_classes: '046t'},
   # following is also half-diminished 7th
-  {name: 'Min 7th b5', abbr: ['ø', 'Ø', 'm7b5'], pitch_classes: '036t'},
+  {name: 'Min 7th b5', abbrs: ['ø', 'Ø', 'm7b5'], pitch_classes: '036t'},
   {name: 'Dim Maj 7th', abbr: '°Maj7', pitch_classes: '036e'},
   {name: 'Min Maj 7th', abbrs: ['min/maj7', 'min(maj7)'], pitch_classes: '037e'},
   {name: '6th', abbrs: ['6', 'M6', 'M6', 'maj6'], pitch_classes: '0479'},

# chord_page Chords[0], best_fingering: true
# intervals_book by_root: true
# intervals_book by_root: false
chord_book best_fingering: 1, pages: 1#, only: 'G#'
# chord_fingerings_page Chords[0], 44 + 3

    return unless interval_class_between(root_note_number, pitch_number_for_position(finger_position)) == semitones
    positions.push finger_position
  return positions

find_barres = (positions) ->
  fret_rows = for fn in FretNumbers
