How HID relates to the event interface

There is a character event device created for each USB HID interface (that has an application field that indicates it is an input device), and potentially for other input devices (if any) that are attached to the system. Note that a single device may have more than one HID interface (for example, some "multimedia" keyboards have the additional buttons on a seperate interface, since they can't be supported by the boot protocol) and hence may have more than one event device.

This event interface is in addition to other, legacy, character devices that may also be created (for example, normal keyboard input, /dev/input/mouse0 and /dev/input/mice, or /dev/input/js0). Refer to the next Chapter for options for these legacy character devices.