Feb 25, 2015 · 4 min read

On Digital Formats

As a digital only publisher, we get asked a lot about digital formats. It’s a complicated question with a very simple answer. The formats we use are the formats that make the most sense for the content. That sounds like an evasion, maybe, but it isn’t. It is an acknowledgement that it actually takes careful consideration and that there isn’t — shock-horror! — a single answer that applies in all cases all of the time.

So what are our options, and when are they appropriate?


This essentially means EPUB and Mobi formats. Run-of-the-mill ebooks available from a wide range of digital retailers, these are obviously the dominant digital format. They are appropriate for anything text-heavy, with a linear structure.

In technical terms, ebooks are a zip container for HTML and CSS files with some XML that gives them structure and an order. There is some room for limited Javascript, but mainly ebooks are static files — documents to be displayed, rather than programs to be run.

Ebooks offer simplicity and convenience delivered through digital bookstores. They are digital products, yes, but they are more book-like than anything else in the digital world, by design. They have limitations that mean more complex structures or interactivity require you to move on to…


By this we mean mobile apps: anything that is being delivered not through digital bookstores (eg the iBookstore), but instead through the digital storefronts built in to nearly every smartphone or tablet out there (eg the App Store). Because of their inherent complexity, we’ll need to unpack this category a bit more. When are these appropriate?

First off, it is important to note that anything that would fit well into ebook formats are almost certainly not a good candidate for an app. We’re introducing a lot of complexity for not a lot of gain.

Apps are genuine programs, written in Objective-C for iOS or Java for Android. Here almost anything is possible, but everything is harder. You aren’t just creating a document to be opened, but the logic of a program to be executed.

Apps are appropriate, or indeed necessary, when features that are not possible in ebook formats are crucial to the experience. Non-narrative non-fiction is an easy example: the interactivity and functionality of Mountain High or Incredible Numbers (disclosure: these are apps the Canelo founders produced in previous roles). The features are open-ended, so focus and scoping are key to making sure you have a successful — and profitable — app.

But what about enhanced ebooks? Or Fixed-layout?

What we usually mean when we say ‘enhanced ebook’ is ‘multimedia ebook’. Adding some audio and video to an ebook is fine, though this isn’t always a huge driver of sales. Support for various kinds of media within ebook formats is spotty at best, and clunky — a narrative that truly blends various forms of media as a key part of the experience is highly likely to require an app framework, so you’re probably better off going down that road instead.

Fixed-layout (FXL) ebooks are print facsimile ebooks: they recreate virtual pages and forsake the reflowable nature of ebooks. These can be appropriate for certain things like children’s picture books or graphic novels, but largely you’re not going to create a fantastic digital product by imposing the restrictions of print onto a digital file without the benefits of having a physical object. Your audience is going to be better served with a genuinely digital product that makes the most of its format, and that probably means one of those two options above.

We hope the above is helpful, but if you have any questions on it we’d be delighted to hear from you, either on twitter or via email. We do a small amount of technical consultancy work, and could advise on the above and more — for further detail please contact me at



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    The New Digital Publisher