static bool less (Spanner *const &, Spanner *const &);
virtual Grob *find_broken_piece (System *) const;
virtual void derived_mark () const;
static bool less (Spanner *const &, Spanner *const &);
virtual Grob *find_broken_piece (System *) const;
virtual void derived_mark () const;
virtual System *get_system () const;
SCM get_cached_pure_property (SCM sym, int start, int end);
virtual System *get_system () const;
SCM get_cached_pure_property (SCM sym, int start, int end);