-  On the ribbon, click 
 (Reference Plane). 
  
- To draw a line: 
- On the Draw panel, click 
 (Line).  
- In the drawing area, draw the reference planes by dragging the cursor. 
 
- Click Modify to end the line. 
 
  
- To pick an existing line: 
- On the Draw panel, click
 (Pick Lines).  
- On the Options bar, specify an offset, if desired. 
 
- Select the Lock option to lock the reference plane to the line. 
 
- Move the cursor near the line to which you want to place the reference plane and click.