Developing Drawing Strategies: Part 1 - AutoCAD 2011 and AutoCAD LT 2011: No Experience Required - page 124

FiGuRE 4.33 Using the Trim Fence option to trim away the unneeded lines
Creating the 7 ′ -0 ″ (2134 mm) opening
Take another look at Figure 4.30 and notice that the opening on the right side
of the building has one jamb set in 4 ′ -6 ″ (1372 mm) from the outside corner.
This opening is for the sliding glass door.