Those string descriptors can be read by the host driver and used to make it more clear what the device is. On Win32 the strings from the INF have precedence over the strings from the device itself. If you omit the strings in the INF (ProviderName, DeviceDesc) then the OS will query and use the strings from the device. You can see the strings in action in the Device Manager. You can query the strings from the INF or the device yourself by using the Setup API. As far as I can see the FriendlyName string is not used on Win32. On Windows CE there are no "inf" files, so Windows CE would use the string descriptors directly from the device.
RE: Thanks for reply, but where
Those string descriptors can be read by the host driver and used to make it more clear what the device is. On Win32 the strings from the INF have precedence over the strings from the device itself. If you omit the strings in the INF (ProviderName, DeviceDesc) then the OS will query and use the strings from the device. You can see the strings in action in the Device Manager. You can query the strings from the INF or the device yourself by using the Setup API. As far as I can see the FriendlyName string is not used on Win32. On Windows CE there are no "inf" files, so Windows CE would use the string descriptors directly from the device.