The device uses the USB communication device class (CDC) drivers to take advantage of the installed PC RS-232 software to talk over the USB. The CDC class is implemented in all releases of Windows®, beginning with Windows 98SE. The CDC document, available at www.usb.org, describes a way to implement devices such as ISDN modems and virtual COM ports.
The Vendor ID (VID) is the Atmel vendor ID 0x03EB. The product ID (PID) is 0x6124. These references are used by the host operating system to mount the correct driver. On Windows systems, the INF files contain the correspondence between vendor ID and product ID.
For more details on VID/PID for end product/systems, refer to the Vendor ID form available from the USB Implementers Forum found at http://www.usb.org/.