The following system and procedure for specifying an extended configuration
descriptor includes a USB device that responds to device requests from a
host. In response to receiving a host-specific device request that
specifies a predetermined index, the USB device returns an extended
configuration descriptor to the requester. The extended configuration
descriptor includes information that can be used by the requestor to
control the USB device. When the USB device is a composite device, the
extended configuration descriptor includes function information
corresponding to a plurality of sub-devices. Each function comprises one
or more interfaces.
