Closes the Twain Data Source manager.
Synopsis
error = TwainCloseDSM()
Returns
An empty string if the data source manager is successfully closed, or an error code not.
Notes
It is not considered an error to call TwainCloseDSM if the data source manager is not open.
TwainCloseDSM automatically calls TwainCloseSource to close any open data source.
If you do not call TwainCloseDSM, then when your main script ends, RXTWAIN.DLL will automatically call TwainCloseDSM for you. So cleanup is done automatically when your main script ends.