For virtual devices that replace standard devices included with Windows, you must use the same virtual device ID numbers as the devices they are replacing. For virtual devices which supplement, rather than replace, the devices in the standard Windows package, you may need to obtain a virtual device ID number from Microsoft DDK Product Support Services (PSS). Virtual device ID numbers are assigned by the DDK PSS. For all virtual devices created from the samples Microsoft provides, you must change the filename. For more information on contacting PSS, see Chapter 2, “Producing Device Drivers and Virtual Devices.”