ADD_ACKNOWLEDGER (Ligature_bracket_engraver, rest);
ADD_ACKNOWLEDGER (Ligature_bracket_engraver, note_column);
ADD_TRANSLATOR (Ligature_bracket_engraver,
ADD_ACKNOWLEDGER (Ligature_bracket_engraver, rest);
ADD_ACKNOWLEDGER (Ligature_bracket_engraver, note_column);
ADD_TRANSLATOR (Ligature_bracket_engraver,