class Key_performer;
class Keyword_ent;
class Keyword_table;
+class Ligature_engraver;
+class Ligature_bracket_engraver;
class Line_group_engraver_group;
class System;
class Local_key_item;
class Melisma_playing_req;
class Melisma_req;
class Melodic_req;
+class Mensural_ligature_engraver;
class Midi_chunk;
class Midi_def;
class Midi_duration;