from page 6 :
<ControlsInfo>
Any action can be controlled by unlimited number of duplicating controls:
<Action name="fire" control="joystick:0:button:5"/>
<Action name="fire" control="Space"/>
<Action name="fire" control="VK_LBUTTON"/>
The sample shows you can fire using either joystick button 6 (5+1) or Space key, or mouse left-click.
Any control assignment can be changed.

Concerning the fire action controls : space key and mouse Left click are OK but I don't understand the comment "joystick button 6 (5+1)"  I just read above "joystick:0:button:5". Doesn't that mean the Button 5 is the active button to fire ?

Is there a way to precise that I'm using the Thrustmaster Hotas Cougar as my joystick ?

and for my info what is VK in VK_LBUTTON ?

Thanks

After some investigation :

1) I now understand why the joystick button 6 (in the exemple above) is assigned to the fire control action. The reason is 5 = 6-1. In other words to assign button 6 you need to write 5.

2) VK means virtual key

That's because of the way FSX "sees" things. Like Window00 is opened with Shift+1, Window01 with Shift+2 etc. Once you get used to it (if you ever do), then it makes things a little bit easier to work with.

It's great that you figured it out on your own too. ;)