Quote:
Originally Posted by jhowell
The mandatory metadata in EPUB varies by version. Newer versions require a modification date.
Metadata in AZW3 format is stored in an EXTH data structure. Calibre fakes the existence of an OPF for editing purposes, but some metadata fields do not translate exactly. |
I think many PG books are in EPUB v2, as I noticed I could use
Polish books to upgrade them to v3. Also, this is probably why I see a date when I check a file exported with
Save to disk or
Send to device, and perhaps why I'm missing the aforementioned fields after converting to .AZW3. Appreciate it.