Communication Functions (3.1)
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 BuildCommDCB             Translates a device-definition string to a DCB
 ClearCommBreak           Restores character transmission
 CloseComm                Closes a communications device
 EnableCommNotification   Enables or disables WM_COMMNOTIFY posting
 EscapeCommFunction       Passes an extended function to a device
 FlushComm                Flushes a transmission or receiving queue
 GetCommError             Retrieves the communications-device status
 GetCommEventMask         Retrieves the device event word
 GetCommState             Retrieves the device control block
 OpenComm                 Opens a communications device
 ReadComm                 Reads from a communications device
 SetCommBreak             Suspends character transmission
 SetCommEventMask         Enables events in a device event word
 SetCommState             Sets the communications-device state
 TransmitCommChar         Places a character in the transmission queue
 UngetCommChar            Puts a character back in the receiving queue
 WriteComm                Writes to a communications device