There are a number of people in the eBook world who really know their ePub format – luckily for us they enjoy sharing this knowledge among the community. One of these such people is Bookworm developer, Liza Daly.
There’s a lot of a misconception around the ePub format with the belief that it is not a very advance format to work with, this is certainly not the case. Being based on several web standards, ePub can do pretty much whatever those standards can do themselves.
In a recent blog post, Liza conducted an experiment to include a HTML5 <video> in an ePub file, which she accomplished by using out-of-island XML mark-up. Okay, so this is something of a hack, and very few ePub readers will render the content (although Bookworm does), but this just goes to show there’s some power in the ePub standard.
All you ePub developers out there might want to keep an eye on Lizas blog as she will be sharing lots of ePub tips throughout this month.
Recently I’ve been making great progress on my ePub converter but in the process I’ve come across a few areas that have needed some thought. For this short article I’m going to discuss the XHTML Quote tag.
When looking though the IDPF OPS specs I noticed that <q> tags are allowed within ePub documents. As I mark up all quotes in my master TEI documents with a <q> tag I was really happy to see this. However, when I came to test my files in Adobe Digital Editions none of my quotes showed.
After seaching around the net I also noticed that <q> tags are not supported by all web browsers (i.e. Internet Explorer). Liza Daly has also noted that the HTML 5.0 specs will depreciate Q tags – will a version of XHTML follow suite in the future? Will a future IDPF OPS spec implement that future XHTML spec?
(FYI, Liza mentioned that she is currently working on implementing <q> tags in her Bookworm reader, with a work around for IE.)
This is an area which I believe ePub developers should give some serious thought over. Even if Adobe DE go ahead and implement this feature, other readers may not necessarily follow suite.
For my own project I have decided to convert all my <q> tags into regular “quote” characters. Providing more safety both now and in the long term.
Liza Daly from threepress.org has just released an article outlining problems she is having with users uploading invalid ePub formatted documents to Bookworm; an online ePub book reader. It’s very important for anyone developing ePub eBooks to produce valid markup. Not only will Bookworm give desirable results when rendering, but you’ll also be covering yourself for any future rendering engines and conversions you might need to do.
It’s actually quite surprising how many errors are showing up from files submitted to Bookworm. You should go over to the threepress blog for a full explanation, but here’s a list of the main errors;
- Missing required attributes in the metadata
- Metadata that hasn’t been proofread
- Improper nesting of the ePub zip file
- Items declared in the OPF file that are missing from the archive
- Invalid XHTML
Points 1 to 4 are really quite vital, although it is understanable for many documents to have invalid XHTML. Still, if it is within your means, I would try to control this the best you can.
I have plans to write some detailed articles regarding the creation of both the NCX and OPF files found in an ePub document, so keep a lookout for those.
If you are looking for a web-based ePub book reader then look no further than Bookworm. Developed by Liza Daly (see also tei2epub Converter), the Bookworm ePub reader will allow you to read ePub books directly from your web browser, there is also a “mobile web-optimized” version for those of you with an iPhone.
The reader is currently in an open-beta status, so as always, expect some bugs and of course many improvements over the coming weeks and months.
To use the reader you will need to create an account on the Bookworm site, all your books will need to be uploaded there. At the moment there is no way to organise your books so if you upload more than a couple dozen, navigation may be a little cumbersome. Liza is working to improve this.
Unlike most other ePub readers, Bookworm allows for full use of stylesheets and images, which is especially critical for technical books which include HTML tables and code samples.