struct Engraver_group_engraver;
struct Request;
struct Request_column;
-struct Request_engraver;
+struct Engraver;
struct Rest;
struct Rest_collision;
struct Rest_collision_engraver;
struct Vertical_brace;
struct Vertical_spanner;
struct Vertical_group;
-
+struct Vertical_align_spanner;
+struct Vertical_align_engraver;
+struct Vertical_align_element;
struct Voice;
struct Voice_element;
struct Voice_group_engravers;