Can't decipher remaining EPUB validation errors

[sgirsberger]

Hello. I have four errors remaining from my ePUBChecker report, and I'm at a loss to figure what they are, although I think they relate to EPUB 3 instead of EPUB 2.

Here are the errors:

ERROR: /Users/shawngirsberger/Documents/MM/EBOOKS/Hanna/working/hanna_book3.epub/OEBPS/content.opf(2): bad value for attribute "version"
ERROR: /Users/shawngirsberger/Documents/MM/EBOOKS/Hanna/working/hanna_book3.epub/OEBPS/content.opf(59): attribute "properties" not allowed at this point; ignored
ERROR: /Users/shawngirsberger/Documents/MM/EBOOKS/Hanna/working/hanna_book3.epub/OEBPS/toc.xhtml(8): unknown element "nav" from namespace "http://www.w3.org/1999/xhtml"
ERROR: /Users/shawngirsberger/Documents/MM/EBOOKS/Hanna/working/hanna_book3.epub/OEBPS/toc.xhtml(126): unfinished element

I've attached the guilty files. This was originally a print book laid out in InDesign CS6, which was exported as EPUB 3 -- hence the toc.xhtml file, which doesn't seem to be part of EPUBs generated from ID CS5.5/EPUB 2.

The book looks and functions just fine on an iPad and a NOOK color, but of course, these errors have to be cleared up before I can send this to the distributor. Sigh.

Your advice is greatly appreciated. I hope I will be able to contribute something here some day.

P.S. I will probably deal with the %20 in the file names of the images that have them. I never put spaces in file names any more, but there were in the author's files, and I didn't change them before starting the project. Thanks to some of the posts here, I'll be more diligent about checking for these.

[sgirsberger]

Okay, made the %20 change and then ran the corrected EPUB through Paul Durant's lovely epubcheck 3.0b5. I now have one remaining error:

ERROR: /OEBPS/content.opf(3,56): assertion failed: package dcterms:modified meta element must occur exactly once

Is this because I deleted some of the dc: terms that are irrelevant for this book? I deleted source, relation, and coverage, as I can't determine what to assign to these, and if I leave them in place, I get error messages.

New content.opf is attached. Thanks in advance!

[Jim Lester]

for epub3 rules instead of having a dc:date element, you need to have dcterms:modified property, which is what the error is trying to tell you.

However, I'm curious if you really want this to be an EPUB 3 document. I didn't see filetypes that would require an epub3 (such as perhaps an audio file of the drumming in this case), and if the content isn't really making use of EPUB3 capabilities then you would be much better off tagging this as an EPUB2 document.

[sgirsberger]

Thanks, Jim. I suspected that this might be the case, and I should have looked this up in the appropriate place.

It's possible that in another edition, someone may want to add sound files to this EPUB, and so between that and the desire to use the most current format possible, I exported to EPUB3. However, if I simply change the version number to 3.0 from 2.0, I'm not sure what effect that will have on the existing tags and structure. I really don't want to go back through this book and make more changes at this point, when everything is behaving well.

I can make the correction to the dcterms:modified property and then change the version number to see if that affects anything. But I'll certainly plan on exporting to EPUB2, then, in the future for EPUBs that are not multimedia-rich.

[DiapDealer]

Originally Posted by sgirsberger

It's possible that in another edition, someone may want to add sound files to this EPUB, and so between that and the desire to use the most current format possible, I exported to EPUB3.

I think a lot of people make this mistake. Not understanding that "going with the most current format" effectively eliminates the vast majority of potential customers/devices/retailers their ebook will actually work for.

[sgirsberger]

Ah, DiapDealer, but I'm willing to learn from my mistakes.

Thanks to Jim's reply, I changed the version number to 2.0 in the content.opf, removed the toc.xhtml file from the OEBPS folder, and deleted the reference to that file from the content.opf. Validated fine as 2.0.

I appreciate the hand-holding. Sometimes it's exactly what I need. And I'm always humbled by the kindness and patience shown by the members here.

[DiapDealer]

Originally Posted by sgirsberger

Ah, DiapDealer, but I'm willing to learn from my mistakes.

Absolutely! I didn't mean it disparagingly.
It's easy to see why people would want to utilize the very latest format. It makes sense from a technological standpoint -- where "current" is often synonymous with "damn near outdated." I just don't think it's widely known that very few devices/apps fully support the latest specs. And I don't know of any ebook retailers who actually accept ePub3 submissions. Let alone sell them.

They might make it over that hump someday. But until then, everyone seems to be just cherry picking pieces and parts from ePub3 without really committing/conforming to the actual specs.

[mrmikel]

The dirty secret in all this is that e-ink readers, as currently designed, are going to have trouble supporting epub 3. Their microprocessors are not powerful enough, their display and lower power consumption is based on a static image, like a page of paper. Epub3 all but supposes a computer screen, a more powerful processor and probably net access. These are power drains which make the reader not so much like a paperback you can just pick up.

These characteristics are not going to be easily reconciled.

There are some people that read epubs on their phones. Popups that are great on larger screens may devour the majority of smaller screens...is this progress?

Again, hard to make everyone happy.

These conflicts will slow the adoption of EPUB3.

[sgirsberger]

Thank you both, DiapDealer and mrmikel, for the down-to-earth discussion of the cons of EPUB3 for existing devices. Because 90% of the work I do involves designing textbooks that are currently destined for print first, with many graphics and specialized formatting, I'm beginning to work with fixed-layout EPUBs from InDesign CS6, and so it's my understanding that EPUB3 is a necessity for these, and it's more likely that they will be read on tablet devices. For the other 10% of books that I do, I will definitely stay with EPUB2.

The problems that I had were reasonably easy to solve, and helped me begin to recognize the difference between the two formats within the HTML/XHTML and CSS files.

[DaleDe]

While fixed layout ePub is part of the ePub 3 specification it was only added after the fact that many publishers had already developed their own systems which were really extensions to ePub 2. At this point there has not be agreement on the fixed layout and you will likely need a different one for each device. For reference see our wiki Fixed layout ePub.

Dale

[Jim Lester]

Originally Posted by DaleDe

While fixed layout ePub is part of the ePub 3 specification it was only added after the fact that many publishers had already developed their own systems which were really extensions to ePub 2. At this point there has not be agreement on the fixed layout and you will likely need a different one for each device. For reference see our wiki Fixed layout ePub.

Dale

Unfortunately it is a little worse than what Dale said, but we are working on it.

I'll be a bit a spec geek here - the current FXL document for EPUB3 is an informational document, and while it is intended for inclusion in a spec update is not part of the spec yet. We (the IDPF FXL ad hoc group) are working on updating the document (adding new features), prior to it's inclusion in the spec.

In addition there has been a seperate working group formed: Advanced Hybrid/Layouts, that is looking at how to formalize some of the interesting things that can be done with multiple renditions (think portrait vs landscape, or fixed vs flowable).

Hopefully things will get a little easier for the content authors/publishers after we finish.

[JSWolf]

Originally Posted by Jim Lester

Unfortunately it is a little worse than what Dale said, but we are working on it.

I'll be a bit a spec geek here - the current FXL document for EPUB3 is an informational document, and while it is intended for inclusion in a spec update is not part of the spec yet. We (the IDPF FXL ad hoc group) are working on updating the document (adding new features), prior to it's inclusion in the spec.

In addition there has been a seperate working group formed: Advanced Hybrid/Layouts, that is looking at how to formalize some of the interesting things that can be done with multiple renditions (think portrait vs landscape, or fixed vs flowable).

Hopefully things will get a little easier for the content authors/publishers after we finish.

But can this standard group help get rid of the multimedia garbage that's part of ePub 3 that's preventing it from being adopted?

[DaleDe]

Originally Posted by Jim Lester

Unfortunately it is a little worse than what Dale said, but we are working on it.

I'll be a bit a spec geek here - the current FXL document for EPUB3 is an informational document, and while it is intended for inclusion in a spec update is not part of the spec yet. We (the IDPF FXL ad hoc group) are working on updating the document (adding new features), prior to it's inclusion in the spec.

I was trying to be kind with my comment. Appreciate the correction and honesty.

Dale

[sgirsberger]

Thank you all for this additional information. I'm finally able to focus on this again.