ZOOM allows you to temporarily alter the size of your part
for easier manipulation. It is especially useful when you
are working on an intricate part and want to add finite
details, or selecting entities that are hard to get at. 
All of these options have assigned Immediate Mode 
commands.

Alter the size of your part by choosing from the following
options:

HALF   - to automatically reduce the part display to 
         one-half the current size.

DOUBLE - to automatically increase a part display to twice
         its size.

SCALE  - to automatically increase or decrease the 
         displayed size of a part to a scale you define.

WINDOW - 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.

AUTO   - to automatically scale the entire working part to
         fit within the viewport.

BACK-1 - to toggle the display between two scales (e.g.,
         AUTO, DOUBLE, HALF).

