Each message received by the auxMessage function comes with two DWORD parameters. For some messages, one of these parameters points to a structure containing additional information from the client, or to an empty structure for the driver to fill with information for the client.
Auxiliary audio device drivers use the structures listed in the following table. For detailed information on this structure, see the reference section later in this chapter.
AUXCAPS | A driver-filled structure providing a client with information about the capabilities of an auxiliary audio device. |