Go to a real console (tty1, tty2, etc.) by pressing Ctrl+Alt+F1. Log in, and then execute the following command as root at the prompt:
Now press the Fn key on your keyboard. You may see a message like
atkbd.c: Unknown key pressed (translated set 2, code 0x9e on isa0060/serio0).
atkbd.c: Use 'setkeycodes e01e <keycode>' to make it known.
If you don't see that message, then run the following command to see it (don't have to be root):
If you still do not see that message, then chances are the Fn key on your keyboard is not meant to be used alone. It is probably meant to be used along with other keys on your keyboard to accomplish certain, unconventional tasks -- much like the Fn key on a laptop keyboard.
If you do see the output above, then all you need to do is run the command that is specified in the message, replacing <keycode> with an unused keycode (usually a number between 120 and 255; use the command "dumpkeys" to find an unused keycode). That should get the key working, although I still don't know for what it's used. Note: if you want the changes you have made to always apply, you will have to make the "setkeycodes" command run on startup. You can do this by editing a file in /etc/init.d, such as bootmisc.sh if you have it.