Each time we export a file (pdf, epub, xml), the sistem saves the last 5 exports. Some times one export is one file, some times are some files.
Maybe afther one month, the system could delete the older exports and to save just one of each format. In that way we could save space in the hard drive, because we use to forget to delete such files and in my situation, I have books with images and each export takes more than 20 mb. We need to have the last one available, but the olders I don´t believe.