QuarkXpress supports the ePUB format so using it, users should be able to export XDOC documents as EPUB publications. Possibly the only way how to perform XDOC to EPUB conversion as *.xdoc files are exclusive to QuarkXpress.
Convert QuarkXPress 3.0 document file to Open Publication structure eBook.
We have found 2 software records in our database eligible for .xdoc to .epub file format conversion.
Microsoft Windows software - convert xdoc to epub on Windows
A design software used to create rich documents for web or print
Convert from xdoc 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 xdoc to epub. 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.
Apple macOS / Mac OS X software - convert xdoc to epub on OS X
Software fro document design and publishing