typedef struct _CM_SERIAL_DEVICE_DATA {
USHORT Version;
USHORT Revision;
ULONG BaudClock;
} CM_SERIAL_DEVICE_DATA, *PCM_SERIAL_DEVICE_DATA;
CM_SERIAL_DEVICE_DATA defines a device-type-specific data record that is stored in the \\Registry\Machine\Hardware\Description tree for a serial controller if the system can collect this information during the boot process.