$#Edit > Add Polyline Vertex
1.Select Edit > Add Polyline Vertex.
2.Move the mouse crosshairs to the location on the polyline where you want to insert the vertex.
3.Single click the mouse button.The vertex is inserted.
4.Move the mouse and you will see the new location of the vertex.
5.Move the vertex to the correct location and click the mouse button again. The vertex is placed.
6.Press the [ESC] key to deselect the command.