In LibreOffice 5.0 I used to be able to open an Open Document file (e.g. *.ods or *.odb) on a low level by unzipping it. Then I could change something there on the “low level”, zip it again and use it. I used the Ubuntu archive manager to do that.
Since Ubuntu 18.4 and LibreOffice 6.0 this does not work any more. The archive manager does not open it (“archive type is not supported”). However, if I open it with the utility “unzip” into a folder (that still works!) and, without changing anything, zip it again (put it into a zip-archive “Filename.zip” and change the extension from “.zip” to e.g., “.odb”), then LibreOffice cannot open it; it considers the file corrupt.
a) Did the file format change?
b) What can I do if I need to make low level changes to an Open Document file?
Thanks for an answer!