WINDOW allows you to designate a portion of the part to be
displayed by positioning a flexible window around it. The
windowed portion of the part is then expanded to occupy 
the entire viewport. This option has an assigned Immediate
Mode command.

Specify the first corner of the window by moving the
cursor to a location on the screen and pressing the cursor
button.

Surround an area or entity part with the rubberbox window
by moving the cursor horizontally and vertically. When the
area you want to enlarge is contained within this box,
press the cursor button.

The box and its contents expand to fill the viewport
limits.
