+ ADD_LISTENER (Slur_proto_engraver, slur);
+ ADD_LISTENER (Slur_proto_engraver, note);
+ ADD_ACKNOWLEDGER (Slur_proto_engraver, inline_accidental);
+ ADD_ACKNOWLEDGER (Slur_proto_engraver, fingering);
+ ADD_ACKNOWLEDGER (Slur_proto_engraver, note_column);
+ ADD_ACKNOWLEDGER (Slur_proto_engraver, script);
+ ADD_ACKNOWLEDGER (Slur_proto_engraver, text_script);
+ ADD_ACKNOWLEDGER (Slur_proto_engraver, dots);
+ ADD_END_ACKNOWLEDGER (Slur_proto_engraver, tie);
+ ADD_ACKNOWLEDGER (Slur_proto_engraver, tuplet_number);