[BobC]

Thanks to all for the ideas - I already have a tristate column that I use to show that the book has been updated, however the problem is in tracking to which devices the updated version has been transferred.

It would need six or seven other columns (one for each device) and a lot of manual updating to do this which is why I was looking for some way of easily comparing file dates (though thinking about it that may not work as the devices filestamp probably reflects when the file was uploaded rather than the original library filestamp date).

I just didn't want to have to do device updates on a stack of readers each time I edited a book.

At least I know that the problem isn't a matter of using an add-on I hadn't heard of or using some less obvious facility of Calibre itself.

Perhaps the simplest way would be an old-fashioned paper form - fill in when I update a book and tick off the devices when I update them.


BobC