Missing a FILENAME entry in the OUTPUT section of configuration file

I miss the possibility to shape the name of the output file in the OUTPUT section of the *.ini configuration file. Moreover, there is no indication/documentation whatsoever on the way the output filename is built in the background.I only know by 'chance' that CSV_ID will be used for a SMET output; I don't know whether this would also work with a BUFR output though.