typedef struct _COMSTAT { // cst  
    DWORD fCtsHold : 1;   // Tx waiting for CTS signal 
    DWORD fDsrHold : 1;   // Tx waiting for DSR signal 
    DWORD fRlsdHold : 1;  // Tx waiting for RLSD signal 
    DWORD fXoffHold : 1;  // Tx waiting, XOFF char rec'd 
    DWORD fXoffSent : 1;  // Tx waiting, XOFF char sent 
    DWORD fEof : 1;       // EOF character sent 
    DWORD fTxim : 1;      // character waiting for Tx 
    DWORD fReserved : 25; // reserved 
    DWORD cbInQue;        // bytes in input buffer         DWORD cbOutQue;       // bytes in output buffer 
} COMSTAT, *LPCOMSTAT; 

 type
  TComStateFlag = (fCtlHold, fDsrHold, fRlsHold, fXoffHold, fXOffSent, fEof,fTxim);  // not in Windows Headers
  TComStateFlags = set of TComStateFlag;
  _COMSTAT = record
    Flags: TComStateFlags;
    Reserved: array[0..2] of Byte;
    cbInQue: DWORD;
    cbOutQue: DWORD;
  end;
  {$EXTERNALSYM _COMSTAT}
  TComStat = _COMSTAT;
  COMSTAT = _COMSTAT;
  {$EXTERNALSYM COMSTAT}
  PComStat = ^TComStat;