want to see "the light" on Thinkpad
 

I have a Thinkpad (7764-CTO) laptop. The PgUp key
has a "blue key" special function which I would access using
Fn + PgUp. The special "blue key" icon
is that of a light bulb shining downward.

Does anyone know what this is supposed to do?

Does anyone know how to make it work?

Thanks,
~~~ 0;-Dan

It is keyboard light, it is located above display. It does not need any software.
http://www.thinkwiki.org/wiki/ThinkLight