Panasonic CF-T2 Series Reference Manual page 10

LED Indicators
NumLk
(Numeric key)
ScrLk
(Scroll lock)
Hard disk drive status
SD memory card status
These indicators light green when NumLk is pressed. When the green
light is on, if the Fn is pressed along with keys on certain other segments of
the keyboard, then those keys will operate as numeric keys. The [Enter] key
functions differently depending on the application.
This indicator lights green when Fn + ScrLk are pressed. Scroll lock
functions differently depending on the application.
This indicator lights when the hard disk drive is accessed.
This indicator lights when the SD memory card or MultiMedia Card is
accessed.
*1
When the AC adaptor is connected.
10