So I edited the metadata of a book (I put 2008-10-12 in the date field and 2010-12-14 in the published field), opened metadata.opf from the book folder and found these:
Code:
<dc:date>2010-12-13T23:00:00+00:00</dc:date>
<meta content="2008-10-11T22:00:00+00:00" name="calibre:timestamp"/>
So the "date" field has the "calibre:timestamp" tag and the "published" field has the "dc:date" tag, as eschwartz already pointed out.
Next, I put
Code:
<meta content="2010-12-13T23:00:00+00:00" name="dc:date" />
<meta content="2008-10-11T22:00:00+00:00" name="calibre:timestamp" />
in the content.opf file of the EPUB.
I remove the book from the calibre library, and add the modified one.
In the metadata.opf file I find:
Code:
<dc:date>2014-04-08T22:00:00+00:00</dc:date>
<meta content="2014-04-09T09:39:48.364000+00:00" name="calibre:timestamp"/>
which is not what I've put in.
Observations:
1) calibre does not interpret the content.opf file of the EPUB correctly.
2) calibre uses different rules for the timezone (I'm in UTC+2).
If I enter 2008-10-12 in the DATE field in the UI, calibre subtracts 2 hours
If I enter 2010-12-14 in the PUBLISHED field, calibre subtracts 1 hour
Apart from the fact that it is nonsense to store a published date with a time part, the rules must be the same.
3) The date field is saved in a different format: the result of editing in the UI saves the date up to seconds (without fractional part) while when adding a book, the date is saved up to 1 millionth of a second.
(let's not get distracted by observations 2 and 3, the real problem is observation 1)
-=Wim=-