Here's an example of fencing:

• Draw a rectangle with lines protruding through the edges, as shown.
   
• Enter "tr" for Trim.
• Select the rectangle and right click or click Enter.
• Enter "f" for Fence.
• Draw a fence line through the objects that you would like to trim, as shown.
   
• Right click (or click Enter) twice.
• This is what you should end up with:
   

The best use I find for "fencing" is when I am drawing up full-height backsplash panels that have a diagonal scoring pattern. I draw an oversized scoring pattern, place the backsplash panel where I want the scoring pattern to line up, and then trim the lines.

 About the Author:  Seth Emery is a CAD Drafter/CNC Programmer for Henry H. Ross & Son, Inc. in Lititz, Pennsylvania.  H.H.  Ross specializes in the fabrication and installation of solid surface, granite, and engineered stone countertops in residential and commercial applications.  Seth can be reached at seth77@ptd.net  Visit the H.H. Ross website at http://www.hhross.com