class Event_chord;
class Event_chord_iterator;
class Event_iterator;
-class Folded_repeat_iterator;
class Font_metric;
class Font_size_engraver;
class Global_context;
class Simultaneous_music_iterator;
class Skyline;
class Skyline_entry;
+class Skyline_pair;
class Slur_configuration;
class Slur_score_state;
class Source_file;