DECLARE_SCHEME_CALLBACK (offset_callback, (SCM element));
DECLARE_SCHEME_CALLBACK (calc_direction, (SCM));
DECLARE_SCHEME_CALLBACK (calc_beaming, (SCM));
DECLARE_SCHEME_CALLBACK (offset_callback, (SCM element));
DECLARE_SCHEME_CALLBACK (calc_direction, (SCM));
DECLARE_SCHEME_CALLBACK (calc_beaming, (SCM));