ADD_ACKNOWLEDGER (Text_engraver, stem);
ADD_ACKNOWLEDGER (Text_engraver, stem_tremolo);
ADD_ACKNOWLEDGER (Text_engraver, rhythmic_head);
ADD_ACKNOWLEDGER (Text_engraver, stem);
ADD_ACKNOWLEDGER (Text_engraver, stem_tremolo);
ADD_ACKNOWLEDGER (Text_engraver, rhythmic_head);