struct Blank_req;
struct Bow;
struct Box;
-struct Break_align_item;
struct Bracket_req;
+struct Break_align_item;
+struct Break_req;
struct Cadenza_req;
struct Change_iterator;
struct Change_translator;
struct Dots;
struct Dot_column;
struct Directional_spanner;
-struct Disallow_break_req;
struct Durational_req;
struct Dynamic;
struct Dynamic_req;
struct Element_group;
struct Element_group_item;
-struct Break_force_req;
struct General_script_def;
struct Graphical_element;
struct Music_output;