JRC JMA-9832-SA Instruction Manual page 64

$7 [Trackball section right button]
Clears the marks on the display in the MARK mode.
$8 [PWR FAIL] (Power Failure) Lamp
The lamp lights in case of power failure.
$9 [Hand sensor]
When the sensor senses something, the trackball becomes operable.
To acquire target automatically.
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