+ z20 = z9l - (0, .25 blot_diameter);
+ penpos20 (blot_diameter, 0);
+
+ pat := z10{down}
+ .. z6
+ ..tension 1.1.. z11{dir (start_angle)};
+
+ penpos6 (thinnib, angle (direction 1 of pat) + 90);
+
+ % two auxiliary points to simulate `draw' with `penstroke'
+ z10' = point 0.3 of pat;
+ penpos10' (1.3 thinnib, angle (direction 0.3 of pat) + 50);
+
+ z11' = point 1.5 of pat;
+ penpos11' (thinnib, angle (direction 1.5 of pat) + 90);
+
+ z21l = z20l;
+ z21r = z9r;
+
+ pat := z21l
+ .. z10l{down}
+ .. z10'l;
+