Casio IT-2000W Technical Reference Manual page 238

CloseYMODEM
If this function is called, the use of YMODEM library is completed, and the COM port is closed.
SYNTAX
#include "ymodem.h"
short WINAPI _export CloseYMODEM( void )
INPUT
None
OUTPUT
= 0
= Other Refer to the error code table.
Normal termination
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