diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -363,6 +363,12 @@ These examples incubate dotSCAD and dotSCAD refactors these examples. See [examp
 
 # Preview
 
+## 2D/3D Function
+
+ Signature | Description
+--|--
+[**rails2sections**(rails)](https://openhome.cc/eGossip/OpenSCAD/lib3x-rails2sections.html) | create sections along rails.
+
 ## Transformation
 
  Signature | Description
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-# rail_extruded_sections
-
-Given a rail with the first point at the outline of a shape. This function uses the rail to extrude the shape and returns all sections in the reversed order of the rail. Combined with the `sweep` module, you can create rail extrusion. 
-
-In order to control extrusion easily, I suggest using `[x, 0, 0]` as the first point and keeping y = 0 while building the rail.
-
-**Since:** 3.2
-
-## Parameters
-
-- `shape_pts` : A list of points represent a shape.
-- `rail` : A list of points represent the edge path.
-
-## Examples
-
-	use <hull_polyline3d.scad>;
-	use <shape_taiwan.scad>;
-	use <rail_extruded_sections.scad>;
-	use <sweep.scad>;
-
-	taiwan = shape_taiwan(100);
-	fst_pt = [13, 0, 0];
-
-	rail = [
-		fst_pt,
-		fst_pt + [0, 0, 10],
-		fst_pt + [10, 0, 20],
-		fst_pt + [8, 0, 30],
-		fst_pt + [12, 0, 40],
-		fst_pt + [0, 0, 50],
-		fst_pt + [0, 0, 60]
-	];
-
-	#hull_polyline3d(rail);
-	sweep(rail_extruded_sections(taiwan, rail));
-
-![rail_extruded_sections](images/lib3x-rail_extruded_sections-1.JPG)
-
-	use <hull_polyline3d.scad>;
-	use <shape_taiwan.scad>;
-	use <rail_extruded_sections.scad>;
-	use <sweep.scad>;
-	use <bezier_curve.scad>;
-
-
-	taiwan = shape_taiwan(100);
-	fst_pt = [13, 0, 0];
-
-	rail = bezier_curve(0.05, [
-		fst_pt,
-		fst_pt + [0, 0, 10],
-		fst_pt + [10, 0, 20],
-		fst_pt + [8, 0, 30],
-		fst_pt + [12, 0, 40],
-		fst_pt + [0, 0, 50],
-		fst_pt + [0, 0, 60]
-	]);
-
-	#hull_polyline3d(rail);
-	sweep(rail_extruded_sections(taiwan, rail));
-
-![rail_extruded_sections](images/lib3x-rail_extruded_sections-2.JPG)
-
-	use <shape_taiwan.scad>;
-	use <rail_extruded_sections.scad>;
-	use <sweep.scad>;
-	use <bezier_curve.scad>;
-	use <ptf/ptf_rotate.scad>;
-
-	taiwan = shape_taiwan(100);
-	fst_pt = [13, 0, 0];
-
-	rail = bezier_curve(0.05, [
-		fst_pt,
-		fst_pt + [0, 0, 10],
-		fst_pt + [10, 0, 20],
-		fst_pt + [8, 0, 30],
-		fst_pt + [12, 0, 40],
-		fst_pt + [0, 0, 50],
-		fst_pt + [0, 0, 60]
-	]);
-
-	leng = len(rail);
-	twist = -90;
-	twist_step = twist / leng;
-	sections = rail_extruded_sections(taiwan, rail);
-
-	rotated_sections = [
-		for(i = [0:leng - 1]) 
-		[
-			for(p = sections[i]) 
-				ptf_rotate(p, twist_step * i)        
-		]
-	];
-
-	sweep(rotated_sections);
-
-![rail_extruded_sections](images/lib3x-rail_extruded_sections-3.JPG)	
-
-	use <hull_polyline3d.scad>;
-	use <shape_taiwan.scad>;
-	use <rail_extruded_sections.scad>;
-	use <sweep.scad>;
-    use <ptf/ptf_rotate.scad>;
-
-	taiwan = shape_taiwan(100);
-
-    /* 
-	    You can use any point as the first point of the edge path.
-		Just remember that your edge path radiates from the origin.
-	*/
-	fst_pt = [taiwan[0][0], taiwan[0][1], 0];//[13, 0, 0];
-    a = atan2(fst_pt[1], fst_pt[0]);
-	rail = [
-		fst_pt,
-		fst_pt + ptf_rotate([0, 0, 10], a),
-		fst_pt + ptf_rotate([10, 0, 20], a),
-		fst_pt + ptf_rotate([8, 0, 30], a),
-		fst_pt + ptf_rotate([10, 0, 40], a),
-		fst_pt + ptf_rotate([0, 0, 50], a),
-		fst_pt + ptf_rotate([0, 0, 60], a)
-	];
-
-	#hull_polyline3d(rail);
-	sweep(rail_extruded_sections(taiwan, rail));
-
-![rail_extruded_sections](images/lib3x-rail_extruded_sections-4.JPG)
\ No newline at end of file
diff --git a/docs/lib3x-rails2sections.md b/docs/lib3x-rails2sections.md
index 52675bd8..910c115c 100644
--- a/docs/lib3x-rails2sections.md
+++ b/docs/lib3x-rails2sections.md
@@ -1,6 +1,6 @@
 # rails2sections
 
-It returns all cross-sections described by rails. Combined with the `sweep` module, you can describe a more complex model.
+Create sections along rails. Combined with the `sweep` module, you can describe a more complex model.
 
 Rails should be indexed count-clockwisely.