DECLARE_SCHEME_CALLBACK (y_offset_callback, (SCM));
DECLARE_SCHEME_CALLBACK (calc_cross_staff, (SCM));
DECLARE_GROB_INTERFACE ();
DECLARE_SCHEME_CALLBACK (y_offset_callback, (SCM));
DECLARE_SCHEME_CALLBACK (calc_cross_staff, (SCM));
DECLARE_GROB_INTERFACE ();