ADD_ACKNOWLEDGER (Mensural_ligature_engraver, rest);
ADD_ACKNOWLEDGER (Mensural_ligature_engraver, note_head);
ADD_TRANSLATOR (Mensural_ligature_engraver,
ADD_ACKNOWLEDGER (Mensural_ligature_engraver, rest);
ADD_ACKNOWLEDGER (Mensural_ligature_engraver, note_head);
ADD_TRANSLATOR (Mensural_ligature_engraver,