Apple PowerBook (Duo, 2300 Series) - Manual (Page 136)

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 (connected to a dock), 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 screen brightness when you take the computer
from one work location to another, or if the lighting in your work area
changes.
129 Health, Safety, and Maintenance Tips