arrowname = aname [ aname [ aname [ aname ] ] ] aname = [ modifiers ] shape modifiers = [ 'o' ] [ side ] side = 'l' | 'r' shape = T_box | T_crow | T_curve | T_icurve | T_diamond | T_dot | T_inv | T_none | T_normal | T_tee | T_vee
