+struct Element_group;
+struct Element_group_item;
+struct Engraver_group_engraver;
+struct General_script_def;
+struct Graphical_element;
+
+struct Graphical_axis_group;
+struct Mark_req;
+struct Music_output;
+struct Musical_pitch;
+struct Music_output_def;
+struct Global_translator;
+struct Hara_kiri_line_group_engraver;
+struct Hara_kiri_vertical_group_spanner;
+struct Head_column;
+
+struct Horizontal_align_item;
+struct Horizontal_group_element;
+struct Horizontal_group_item;
+struct Horizontal_vertical_group;
+struct Idealspacing;
+struct Identifier;
+struct Input_file;
+struct Item;
+struct Key;