Developing Drawing Strategies: Part 1 - AutoCAD 2011 and AutoCAD LT 2011: No Experience Required - page 152

12. Enter O ↵ or click Offset on the Home tab ➢ Modify panel to start the
OFFSET command, and then enter 1 ↵ ( 25 ↵ ) to set the offset distance
to 1 ″ (25 mm).
13. Select the horizontal line you just drew, and then pick a point in a
blank area anywhere above the line. Pick the first horizontal line
again, and then pick anywhere below it.
The new line has been offset 1 ″ (25 mm) above and below itself (see
Figure 4.68). Now you have placed all the lines necessary to create
the sliding glass door frames in the opening. You still need to trim
back some of these lines and erase others. Press ↵ to end the OFFSET
command.
FiGuRE 4.68 The offset horizontal guideline
14. Start the TRIM command. When you're prompted to select cutting
edges, pick the two horizontal lines that were just created with the
OFFSET command and press ↵ .
15. Trim the two outside vertical lines by selecting them, as shown on
the left of Figure 4.69. The result is shown on the right.