COM_SFLUSH()
 Deletes the sending background buffer

 Syntax

     COM_SFLUSH(<nComPort>) --> lDeleted

 Argument

     <nComPort>  Designates the port (1 to N) for which the sending
     buffer is deleted.

 Returns

     If the selected sending buffer is successfully deleted, the function
     returns a .T.

 Description

     COM_SFLUSH() eliminates all the characters in a sending buffer.  This
     can be useful when the send routine has been futilely waiting for an XON
     character (bad software handshake).

 Notes

     ”  A COM_SFLUSH() to a closed port does not work.

     ”  It is not necessary to test for characters in the sending
        buffer to carry out a COM_SFLUSH().

 Example

     COM_SEND(2, cSendText)