+ DECLARE_GROB_INTERFACE ();
+ static int get_rank (Grob const *);
+ static bool is_musical (Grob *);
+ static Moment when_mom (Grob *);
+ static bool is_used (Grob *);
+ static bool is_breakable (Grob *);
+ static bool is_extraneous_column_from_ligature (Grob *);
+ static Real minimum_distance (Grob *l, Grob *r);
+ static Interval break_align_width (Grob *me, SCM align_sym);
+ static Interval get_interface_extent (Grob *column, SCM iface, Axis a);