Convert DOC to OPF

doc to opf conversion is most likely related to the process of making OPF ebooks from MS Word documents, something that might be possible albeit a little tricky due to limited support for OPF format. OPF or Open Packaging Format is pretty much the grandfather of the now common EPUB, unfortunately support for it is no longer common. Your best hope lies in one of the dedicated ebook converters or ebook management software like Calibre.