struct Absolute_dynamic_req;
+struct Abbreviation_req;
+struct Abbreviation_beam_req;
+struct Abbreviation_beam_engraver;
struct Axis_group_element;
struct Axis_group;
struct Translator;
struct Bar_req;
struct Barcheck_req;
struct Beam;
+struct Beam_engraver;
struct Beam_req;
struct Blank_req;
struct Box;