Fork 

Create a line (A-B) connecting a major top and bottom, and then click on a third point (C). This will create the lines A, B and C shown on the chart to the right.

You have the option of displaying extra lines that show an inside retracement of 38.2% and 61.8% of (A-B) as well as  3 expansions lines from A and B using expansions of 38.2%, 50% and 61.8%.

The Fork Parameters window allows you to change color and line thickness and which lines to display.