In the kernel-streaming architecture, topology categories (see KSPROPERTY_TOPOLOGY_CATEGORIES) represent device interface classes. For each device interface, the INF file specifies a FriendlyName entry value, which is accessible in user mode, under the interface's registry key.
The device interfaces specified in the INF file have a one-to-one correspondence with the subdevices that the adapter driver creates when it initializes the device (see Subdevice Creation). A client accesses an audio device through a set of device interfaces that a vendor specifies in the adapter's INF file.