+ static bool has_interface (Grob*);
+ virtual void do_break_processing ();
+ virtual Paper_column *get_column () const;
+ virtual System *get_system () const;
+
+ static int get_rank (Grob*);
+
+ DECLARE_SCHEME_CALLBACK (print, (SCM));
+ DECLARE_SCHEME_CALLBACK (before_line_breaking, (SCM));
+
+ static bool is_musical (Grob *);
+ static Moment when_mom (Grob*);
+
+ static bool is_used (Grob*) ;