struct Absolute_dynamic_req;
+struct Abbreviation;
struct Abbreviation_req;
struct Abbreviation_beam_req;
struct Abbreviation_beam_engraver;
struct Beam_engraver;
struct Beam_req;
struct Blank_req;
+struct Bow;
struct Box;
struct Break_align_item;
struct Bracket_req;
struct Dynamic_req;
struct Element_group;
struct Element_group_item;
+struct Break_force_req;
struct General_script_def;
struct Graphical_element;
struct Music_output;
struct Paper_def;
struct Partial_measure_req;
struct Plet;
+struct Plet_engraver;
+struct Plet_req;
+struct Plet_spanner;
struct Pulk_voice;
struct Pulk_voices;
struct Rational;