HID - Human Interface Devices, is a way of directly grabbing the data from USB devices attached to the computer through DirectX Hardware Adapter Layers
basically it a direct route to any controllers which tend not to natively use DirectInput and allow you to access them as Joysticks.
This is all within the help files - F1 will bring them up and i'd suggest you check the command lists and examples.
Tsu'va Oni Ni Jyuuko Fiori Sei Tau!
One block follows the suit ... the whole suit of blocks is the path ... what have you found?