Hard Drive/Optical Drive Access Indicator; Numlk Indicator; Capslock Indicator; Scrlk Indicator - Fujitsu FPCR46001 User Manual

Hard Drive/Optical Drive Access Indicator

The Hard Drive/Optical Drive Access indicator glows when your internal hard drive is being accessed.
Note that flickering is normal.
NumLk Indicator
The NumLk indicator glows when the integral keyboard is set in ten-key numeric keypad mode. 

CapsLock Indicator

The CapsLock indicator glows when your keyboard is set to type in all capital letters.
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ScrLk Indicator
The ScrLk indicator states that your scroll lock is active.
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21 - Status Indicator Panel