Apple PowerBook (3400 series) - Manual (Page 141)

Some computer users may develop discomfort in their hands, wrists, or arms
after intensive work without breaks. If you begin to develop chronic pain or
discomfort in your hands, wrists, or arms, consult a qualified health
specialist.
m Change hand positions often to avoid fatigue.
m If you prefer, you can adjust the angle of the keyboard by lowering the
elevation feet until they snap into position.
The back of the keyboard is slightly elevated when the feet are in use.
Otherwise, the keyboard is level.
Mouse
m If you use an external mouse, position the mouse at the same height as
your keyboard. Allow adequate space to use the mouse comfortably.
Built-in display
m Adjust the angle of the display to minimize glare and reflections from
overhead lights and windows.
m You may need to adjust the brightness and contrast of the screen when you
take the computer from one work location to another, or if the lighting in
your work area changes.
To lower the foot, press the release
button. The foot extends automatically. To raise the foot, press the release button while
pushing up on the foot until it clicks into place.
141 Health, Safety, and Maintenance Tips