"Office Isolated Converter Environment" is the internal name of the Fileformatconvertor (as far as I know), but "oice" is also the commandline option for silent standalone conversion. Conversion xlsx-to-xls or xls-to-xlsx is possible in three ways, all working in my 98SE installation, KernelEx compatibility modes as above. Xlsx to xls only in two ways, Excelcnv gives a xlsx-file with extension xls! I. Use Shell option "Save as" with dialogs, choice of extension etcetera. Uses Moc.exe II. Use commandline for Moc.exe: Moc -f "Station\Path\File". Extension xlsx or xls. Further same as Shell option. III. Silent commandline with Excelcnv.exe: Excelcnv -oice "Station\Path\File" "Station\Path\File". First extension existing, second target.