I just posted something about ONLYOFFICE file support so I thought it relevant to note what FreeOffice lists:
- Microsoft Word files (.DOC, .DOT)
Microsoft Word 2007·2016 files (.DOCX, .DOCM, .DOTX, .DOTM)
OpenDocument files (.ODT, .OTT)
Pocket Word for Windows CE (.PWD, .PWT)
Pocket Word (.PSW)
Microsoft Excel files (.XLS, .XLT)
Microsoft Excel 2007·2016 files (.XLSX, .XLSM, .XLTX, .XLTM)
additional files (.SDC, .CSV, .SLK, .PRN)
Microsoft PowerPoint files (.PPT, .PPS, .POT)
Microsoft PowerPoint 2007·2016 files (.PPTX, .PPTM, .PPSX, .PPSM, .POTX, .POTM)
Rich Text File (.RTF)
When using the install + build portable + uninstall method, just a note that you should also zap the HKEY_CURRENT_USER\SOFTWARE\Softmaker Software GmbH registry key.