COM_SOFT_S()
 Tests to see if the buffer has automatically sent an XOFF character
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 Syntax

     COM_SOFT_S(<nComPort>) --> lXOFFFlag

 Argument

     <nComPort>  Designates the port (1 to 4) for which the XOFF flag is
     tested.

 Returns

     This function returns .T. when the remote station indicates that the
     buffer is 75% or more full.

 Description

     If the software handshake has been selected and the buffer is more than
     75% full, an XOFF character is automatically transmitted to the remote
     station.  This is noted with an internal flag, which can be queried
     using COM_SOFT_S().  When the buffer empties to 50% or less, it
     generates the transmission of an XON character, and this flag is reset.

 Note

     .  When selecting the size of the buffer, decide whether the
        remaining 25% will be sufficient at high baud rates.

 Example

     Test to see if a 75% full buffer automatically transmits an XOFF
     character:

     IF = COM_SOFT_S(1)
        ? "It's time to empty the buffer! "
        ...
     ENDIF