ADD_ACKNOWLEDGER (Phrasing_slur_engraver, fingering)
ADD_ACKNOWLEDGER (Phrasing_slur_engraver, note_column);
ADD_ACKNOWLEDGER (Phrasing_slur_engraver, slur);
ADD_ACKNOWLEDGER (Phrasing_slur_engraver, fingering)
ADD_ACKNOWLEDGER (Phrasing_slur_engraver, note_column);
ADD_ACKNOWLEDGER (Phrasing_slur_engraver, slur);