You got it, BC_programmer.
Now I am ready to drop this. I doubt there is much interest. Digging into the keyboard is very old school stuff. But if anybody wants to get into it, there is a lot written about it. You have to admire how the IBM engineers could over create a keyboard design so many YEARS ago. The keyboard had a significant computing power by itself. The main advantage of the design was that you could handle everything over a serial interface. This allowed the IBM keyboard to have a small thin wire. A fat wire would have reduced the chip count. But IBM made the right choice. Thin is in. Nowadays you buy a standard keyboard for about $12 -retail! Hard to believe.

As for the Fn key, it is used on LAPTOPS. Once source implies that the decoder chip handles it and it is not visible to the BIOS or the OS. Only when you press a second key does the decoder sends it out over the wire, but with a different code than the second key by itself you hit. So it is a hardware modifier.

WINDOWS 7 users will like this:
Remapping keyboard for current user only - Windows 7 Forums
The key code nuts and bolts are in the registry. Has been there for years. Others build on what Microsoft innovated.