EPUB 3 vs. EPUB 2.0

So EPUB 3 is finally out and, given that the IDPF site was down yesterday with what must have been a huge overload of traffic, everyone seems to be as excited about it as we are.

The blogosphere and trade press are already overflowing with articles on the new EPUB standard so we’ll keep this short and sweet and to the point.

EPUB 3 means EPUB (and thus essentially eBooks as a whole now that Amazon looks set to go the EPUB way) will spread to many more markets and readers because we now have:

• Support for complex content (maths, high-design textbooks)
• Enriched content (audio and video)
• Global language support
• Accessibility

Here’s a detailed look at how EPUB 3 compares to EPUB 2.0:

Feature	EPUB 2.0	EPUB  3.0	Impact/Functionalities
HTML 5 <nav>	No	Yes	HTML5 <nav> element supersedes the NCX document. NCX document can also be included for EPUB 2 reading systems forward compatibility purposes.
CSS3 support *	No	Yes	Better control over line break, hyphenation etc. Enables text writing from left to right and right to left.
Multiple style sheets	No	Yes	Supports the ability to include multiple style sheets. Enables dynamic horizontal and vertical layouts.
OTF & WOFF	No	Yes	Allow fonts which are not installed in the end user’s system to be delivered along with the EPUB file. Facilitates the retention of the look and feel of the PDF in the EPUB version.
SVG support	No	Yes	EPUB 3 support to represent vector graphics inline within content as well as standalone SVG file. Pages will be lighter, thus reducing load time, when we use the SVG element to draw shapes.
Metadata	No	Yes	A rich array of options for adding publication metadata to improve global distribution of publications. eg: a Japanese publication could include an alternate Roman-script representation.
epub: type	No	Yes	Allows elements in XHTML to include semantic meanings This addition allows content to be better grouped and defined based on the requirement
epub: trigger	No	Yes	Enables the creation of mark-up defined user interfaces for controlling multimedia objects. Actions include show/hide, play/pause/resume, mute/unmute, etc.
<bindings>	No	Yes	Provides script-based handlers for non-standard media types
XHTML 5 support	No	Yes	Inherits unless otherwise specified all definitions of semantics, structure and processing behaviours from the HTML5 specification
MathML	No	Yes	Direct embedding of MathML supported Advantage for STM publishing as this enables rendering of mathematics as text instead of graphics/images
Scripting	No	Yes	Support for scripted content, ie interactivity, using JavaScript language
Audio & Video	No	Yes	Inherits support for HTML5 rich media elements
Aural renditions & Media Overlays	No	Yes	Provides text-to-speech facility (Pronunciation Lexicons (PLS), Inline SSML Phonemes, CSS speech  features).Enables the usage of SMIL (Synchronized Multimedia Integration Language) for representation of synchronized text and audio.

Features that have been removed:

Feature	EPUB 2.0	EPUB 3.0	Impact/Functionalities
Alternative syntax to XHTML	DTBook	HTML5 semantic markup	DTBook is no longer an alternative syntax
Out-of-Line XML Islands	Yes	No	<item> element no longer has an optional attribute fallback-style
Tours element	Yes	No	Package document no longer includes <tours> element
Guide element	Yes	No	Deprecated in favour of navigation document  <landmarks> feature

Now that EPUB 3 has been released, the impact it has will be largely determined by how fast publishers adopt the standard and how quickly device makers adapt their devices.

 Naren Kumar 

SVP, Production Technology – MPS Limited