Apple Macintosh PowerBook 150 - Manual (Page 64)

m Use a light touch when typing or using the trackball and keep your hands
and fingers relaxed. When using the trackball or keyboard, avoid rolling
your thumbs under your palms.
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 legs
until they snap into position.
The back of the keyboard is slightly elevated when the legs are in use.
Otherwise, the keyboard is level.
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55 Health, Safety, and Maintenance Tips