Some spreadsheet editors (usually those based on OpenFormat specs) support files saved in the Unified Office format (.uos) and thus should be fully capable of saving them to other formats, including .xls spreadsheets used by Microsoft Excel.
Convert Unified Office format spreadsheet file to Microsoft Excel 97 to 2003 workbook.
We found 3 software records in the database related to .uos to .xls file format conversion.
Apple macOS / Mac OS X software - convert uos to xls on OS X
A full-featured set of office applications for Mac OS X
Convert from uos file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned uos to xls. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Multiplatform software - convert uos to xls on any platform
Full-featured spreadsheet tool from LibreOffice suite
Spreadsheet program from OpenOffice.org productivity suite