Function Keys behavior on Lenovo ThinkPad, Fn + Function Key, or just click on F1-F12

Here is another thing I could not find an obvious answer on the web:
Lenovo Thinkpad by default has the function keys assigned to media and other functions: volume, microphone, brightness. For the longest time I could not figure out how to switch it back to the standard Windows FN keys, ie F1 = help, F5 = refresh. I kept hitting F5 and dimming the screen.

Here is how to switch:

Find the FnLk key. On my keyboard it was under the Esc key.
So I typed Fn + Esc and switched it.
Now there is a small LED indicator lit up on the Fn key that I guess shows that I am using default Windows Fn keys.