Looks like people posting here are a little slow. WinXP, Win7 and Win10 all read the buttons on the joystick/throttle has "joy#".
If you have a newer joystick/throttle the software that came with it calls the buttons "Trigger, A, B, Pinkie, H1, H2" but Windows
see and calls them "Joy1=Trigger, Joy2=A, Joy3=B, Joy6=Pinkie, Joy7/Joy8/Joy9/Joy10=H1, Joy11/Joy12/Joy13/Joy14=H2.
I have the Logitech X56 RBG HOTAS and this is what the joystick/throttle calibration windows look like.

Go to this link for images of the joystick/throttle Joy#. (It is for a Saitek X55 Joystick/Throttle)
Joy# for the X55/X56 Joystick/Throttle
This should help anybody that's still looking for the info on Joy#.