Developing Drawing Strategies: Part 1 - AutoCAD 2011 and AutoCAD LT 2011: No Experience Required - page 118

NOTE as you've just seen with the FILLET command, pressing and
holding the Shift key temporarily overrides the normal functionality of the
command. For the FILLET command, the radius is temporarily set to 0 .
When the Shift key is used with the EXTEND command, it temporarily functions
like the TRIM command. Conversely, when used with the TRIM command, it
functions like the EXTEND command.
6. Return to a view of the whole drawing by entering Z ↵ and then P ↵ .
This is the ZOOM command's Previous option, which restores the
view that was active before the last use of the ZOOM command (see
Figure 4.24). This command is also available from the Zoom fly-out
button on the navigation bar.
FiGuRE 4.24 The result of the ZOOM Previous command
Repeat the procedure to trim the lower T-intersection. Follow these steps:
1. Enter Z ↵ , and click two points to make a rectangular zoom window
around the intersection.
2. Start the TRIM command, select the interior walls as cutting edges,
and press the spacebar.
3. Select the inside exterior wall line between the cutting edges.
4. Press the spacebar or ↵ to end the TRIM command.
5. Zoom Previous by entering Z ↵ P ↵ .