Strange button on Fujitsu Siemens Amilo L1310G Laptop

Hi. I was looking at a friends laptop yesterday. I saw a button on the same row as the help, wireless and power buttons. It has a symbol on it that kind of looks like this: michaelgr.files.wordpress.com/2008/01/radioactive-001.png
What is its function? I pressed it but nothing happened! The laptop model is a Fujitsu Siemens Amilo L1310G. The picture of it is here: imgur.com/QYpOy

 

Curious, do you have all the drivers from the manufacturer?

found here: Fujitsu Siemens Amilo L1310G:
http://ts.fujitsu.com/support/downloads.html

manuals are found here too

 

if it looks like a z with a circle around it is for showing power on? is this it?

no, wait, here it is using the link below, navagating to the laptop type...then to manuals, owners...
Silent Mode (whisper mode) - With this button you can reduce the fan to a minimum.

you may not notice this unless the fan is running and then press the button

 

Hi Break_Da. Yes, I think it is called Silent mode. Thank you.

 

You're welcome Ray79, kinda cool to know what you got so you know what you got :-D