diff --git a/docs/lib-polyline2d.md b/docs/lib-polyline2d.md
index 77b6f9dd..3cc49914 100644
--- a/docs/lib-polyline2d.md
+++ b/docs/lib-polyline2d.md
@@ -1,6 +1,7 @@
 # polyline2d
 
-Creates a polyline from a list of `x`, `y` coordinates. It depends on the `line2d` module so you have to `include` line2d.scad.
+Creates a polyline from a list of `x`, `y` coordinates. When the end points are `CAP_ROUND`, 
+* you can use `$fa`, `$fs` or `$fn` to controll the circle module used internally. It depends on the `line2d` module so you have to `include` line2d.scad.
 
 ## Parameters
 
@@ -8,19 +9,21 @@ Creates a polyline from a list of `x`, `y` coordinates. It depends on the `line2
 - `width` : The line width.
 - `startingStyle` : The end-cap style of the starting point. The value must be `"CAP_BUTT"`, `"CAP_SQUARE"` or `"CAP_ROUND"`. The default value is `"CAP_SQUARE"`. 
 - endingStyle : The end-cap style of the ending point. The value must be `"CAP_BUTT"`, `"CAP_SQUARE"` or `"CAP_ROUND"`. The default value is `"CAP_SQUARE"`. 
-- `round_fn` : When the end-cap style is "CAP_ROUND", it controlls the `$fn` value used by the `circle` module. The default value is `24`.
 
 ## Examples
 
+    $fn = 24;
 	polyline2d(points = [[1, 2], [-5, -4], [-5, 3], [5, 5]], width = 1);
 
 ![polyline2d](images/lib-polyline2d-1.JPG)
 
+    $fn = 24;
     polyline2d(points = [[1, 2], [-5, -4], [-5, 3], [5, 5]], width = 1,
                endingStyle = "CAP_ROUND");
 
 ![polyline2d](images/lib-polyline2d-2.JPG)
 
+    $fn = 24;
 	polyline2d(points = [[1, 2], [-5, -4], [-5, 3], [5, 5]], width = 1,
                startingStyle = "CAP_ROUND", endingStyle = "CAP_ROUND");