The Sermouse subkey stores configuration data for the Microsoft serial mouse driver in Windows NT 4.0 and earlier. In Windows 2000, this data appears in the device-specific subkeys of the Enum subkey. However, when you upgrade from Windows NT 4.0 and earlier, some of the values in the Sermouse subkey are copied to the device-specific keys. For details, see the descriptions of the entries in this subkey.