Suggestions

[KevinH]

I can tell you are sceptical but Toxaris is exactly 100% right here. The content.opf inside the epub has many pieces including a manifest listing every book file and its mediatype inside the epub, a spine that tells the reader the sequences of files for reading purposes, a guide to show key locations and starting points of the text (epub2 only generally), and a metadata section where all of the metadata associated with the epub is stored. Most readers parse this file to understand how to "effectively" present the epub. Inside an epub you also have an ncx file that stores a table of contents with links (epub2), or under epub3 a nav file used for toc navigation.

When you actually change things using the metadata gui, you are actually changing information stored inside the metadata section of the content.opf file (internal one not the calibre generated local copy outside the epub).

Hope this makes things clearer.

KevinH

[BetterRed]

@Jack_Graham - to add to the posts form Toxaris and KevinH

The 'metadata.opf' files in calibre book folders serve one purpose only, as the means to restore the library database - 'metadata.db'. Apart from the Library Maintenance->Restore Database feature, the calibre Library Manager makes no use of these files. The calibre Viewer uses the content.opf file within the ePub in its metadata overlay display.

If you look inside a metadata.opf file (with an editor like Notepad++) you'll find it lacks the spine and manifest sections which are essential to an ePub (I think ?), You might also find data related to custom columns that is absent from the corresponding content.opf file contained within the ePub file.

It might have been better if the metadata.opf files in calibre library book folders were named metadata.bak, but with over 3 million active users it's too late to contemplate doing that now.

BR

[Hitch]

Originally Posted by BetterRed

@Jack_Graham - to add to the posts form Toxaris and KevinH

The 'metadata.opf' files in calibre book folders serve one purpose only, as the means to restore the library database - 'metadata.db'. Apart from the Library Maintenance->Restore Database feature, the calibre Library Manager makes no use of these files. The calibre Viewer uses the content.opf file within the ePub in its metadata overlay display.

If you look inside a metadata.opf file (with an editor like Notepad++) you'll find it lacks the spine and manifest sections which are essential to an ePub (I think ?), You might also find data related to custom columns that is absent from the corresponding content.opf file contained within the ePub file.

It might have been better if the metadata.opf files in calibre library book folders were named metadata.bak, but with over 3 million active users it's too late to contemplate doing that now.

BR

And, just because sometimes, a picture is worth a thousand words:

This is an ePUB I use for demo purposes, made from an Agatha Christie novel (introducing Tommy and Tuppence, for those who care about such things...). The OPF is a required part of ANY eBook--ePUB, MOBI...it's not some optional thing. If your eBook works, it's because the OPF is there. It's not like embedding a font--it's an integral, fundamental part of any eBook.

In 1, I've unzipped an ePUB, essentially. In 2, I've located the OPF. In 3, I've popped open the OPF, to show you where the metadata LIVES. If I'd put in a description about this book, it would be on a line within that box (the box obviously gets larger as more meta is added.)


HTH.

Hitch

[Jack_Graham]

Thank you for the information - it does make logical sense.

I am not a ebook maker or expert on this subject, I use the editor to make my life easier and that is all. So the education is greatly appreciated. Hopefully I can put it to use and make this part of my life even easier.

Jack

[Hitch]

Originally Posted by Jack_Graham

Thank you for the information - it does make logical sense.

I am not a ebook maker or expert on this subject, I use the editor to make my life easier and that is all. So the education is greatly appreciated. Hopefully I can put it to use and make this part of my life even easier.

Jack

The guys here are the best! They'll see you right. Best of luck.

Hitch

[eschwartz]

Originally Posted by jackie_w

Just FYI - Kobos can also display Series, Comments, Published date, ISBN, Language

I seem to remember hearing that at least the series in particular (for sideloaded books) requires manual insertion into the device database via a calibre plugin.

So just because a reader can display certain types of metadata does not mean that it knows how to extract that information from the EPUB metadata.

[jackie_w]

Originally Posted by eschwartz

I seem to remember hearing that at least the series in particular (for sideloaded books) requires manual insertion into the device database via a calibre plugin.

So just because a reader can display certain types of metadata does not mean that it knows how to extract that information from the EPUB metadata.

For sideloaded books the database can be manipulated by both the standard calibre Kobo device driver and by calibre plugins.

For Kobo purchases the fields are populated by Kobo (not sure how) ... sometimes with good metadata, sometimes not.

The point I was trying to make is that the default database contains suitably named fields (e.g. Series, SeriesNumber) available for population and the device will automatically display whatever is in those fields. IMO this is a step forward from ignoring Series completely.

ETA: Just for the record, Kobos will read/display the opf content of <dc:description> without help from calibre or anything else.

[eschwartz]

Then it is a point without a distinction.

Sigil doesn't care, Sigil can't manipulate that database, and you will need some other software to do so -- which presumably specializes in metadata (and indeed calibre does) and can therefore offer a much better GUI editor for such.


The fact that Kobos have made a step forward from from ignoring series completely, would be a very relevant point... in the Kobo forum rather than the Sigil forum.

[jackie_w]

When KevinH commented

I know of no other reader besides Calibre that shows much of anything other that title, authors, and date but ...

I merely responded - hopefully in a polite manner - with a bit of info which may have been of minor interest.

You, on the other hand, seem to want to agressively argue about what is considered as harmless comment in the Sigil forum. Since I have no interest whatsoever in childish bickering, I'll leave you to it.

[KevinH]

What I said was ...

I know of no other reader besides Calibre that shows much of anything other that title, authors, and date but ... there are so many generations of readers out there now so who knows. The original reason for these other metadata fields was as search fields that are meant to be used to help catalog and index ebooks. Overly complex html/css can actually impact searchability, which is the primary reason for "metadata", but to each their own. As long as you keep things well-formed for xml parsing, you can put anything you like.

was meant to be informative and not in any way "aggressively argumentative."

For the lfe of me, I can't see how anyone could take it that way.

KevinH

Originally Posted by jackie_w

When KevinH commented

I merely responded - hopefully in a polite manner - with a bit of info which may have been of minor interest.

You, on the other hand, seem to want to agressively argue about what is considered as harmless comment in the Sigil forum. Since I have no interest whatsoever in childish bickering, I'll leave you to it.

[eschwartz]

Kevin,

I think that was referring to me, actually.

Whatever, I don't really care. I saw something that didn't fit into my understanding of Kobos, asked for clarification, and confirmed that it was irrelevant and therefore I shouldn't worry myself about it.
I then moved on...

[theducks]

I find it absurd that The Standards Crew did not mandate a Series Standard in all these years. Do they only read non-fiction?

With no Standard, I can see why this is not handled on many devices. Whatever they (the manufacturer) do is wrong or incompatible

[Toxaris]

Originally Posted by theducks

I find it absurd that The Standards Crew did not mandate a Series Standard in all these years. Do they only read non-fiction?

With no Standard, I can see why this is not handled on many devices. Whatever they (the manufacturer) do is wrong or incompatible

I agree, at least it is fixed for ePUB3. That is one thing they did right.

[Turtle91]

I still haven't dug into the ePub3 standard... What is their correction for Series and SeriesNumber? And does that mean I would need to go back and fix all the ePub2 books where I used the Calibre tags?

[Toxaris]

Originally Posted by Turtle91

I still haven't dug into the ePub3 standard... What is their correction for Series and SeriesNumber? And does that mean I would need to go back and fix all the ePub2 books where I used the Calibre tags?

With the metadata in ePUB3 you can do a lot with series, series numbers and anthologies. Of course this is not backwards compatible with Calibre, no way that the IDPF will use Calibre tags. Also, you can enter more information than with the Calibre tags.

An example given in the documentation:
<dc:title id="t1">The Fellowship of the Ring</dc:title>
<meta refines="#t1" property="title-type">main</meta>

<dc:title id="t2">The Lord of the Rings</dc:title>
<meta refines="#t2" property="title-type">collection</meta>

<dc:title id="t3">THE LORD OF THE RINGS, Part One: The Fellowship of the Ring</dc:title>
<meta refines="#t3" property="title-type">expanded</meta>

or another example:
<dc:title id="t1" xml:lang="fr">Mon premier guide de cuisson, un Mémoire</dc:title>
<meta refines="#t1" property="title-type">main</meta>
<meta refines="#t1" property="display-seq">2</meta>

<dc:title id="t2">The Great Cookbooks of the World</dc:title>
<meta refines="#t2" property="title-type">collection</meta>
<meta refines="#t2" property="display-seq">1</meta>

<dc:title id="t3">The New French Cuisine Masters</dc:title>
<meta refines="#t3" property="title-type">collection</meta>
<meta refines="#t3" property="display-seq">3</meta>

<dc:title id="t4">Special Anniversary Edition</dc:title>
<meta refines="#t4" property="title-type">edition</meta>
<meta refines="#t4" property="display-seq">4</meta>

<dc:title id="t5">The Great Cookbooks of the World:
Mon premier guide de cuisson, un Mémoire.
The New French Cuisine Masters, Volume Two.
Special Anniversary Edition</dc:title>
<meta refines="#t5" property="title-type">expanded</meta>


You can check it here.