The explanation of the analog stick axes needs clarification: "For example, the XBox wired controller has 4 axes (top to bottom, left to right, and two diagonals.)" What's a diagonal axis, if not a linear combination of the vertical and horizontal axes? At minimum, for an Xbox-style controller, you should be seeing a vertical and horizontal axis for each of the two analog sticks, and an axis for each of the two analo…
Even sillier, I'm pretty sure it has 5 axes. Left Stick X and Y, Right Stick X and Y, And another Axis used for the 2 triggers. Yeah, I know how silly that sounds for the triggers, but that's how it works.
That does sound odd, since it's possible to detect the state of the triggers independently. The configuration utility for the Xbox Controller driver that I use allows me to map any of the physical axes to the virtual axes X, Y, Z, Rx, Ry, Rz, and Slider, so I guess that's roughly what's supported by the Windows input APIs. I don't really know how it's reported by the controller, though, other than the fact that it isn't standard USB HID.