Motorola L3391 Owner's Manual page 109

(11) If you need 4,9,16,25 dot of the calibrate, we suggest select
" Advanced Calibration" button to calibrate.
(13) Click on the four sides red points and plus sign on the screen to
calibrate your "PENMOUNT" pen to start using your ML 850's
Touchscreen.
Installing Software Drivers
6-19