Digital Publishing: Are You Getting the Most Out of EPUB 3?

But for backwards compatibility and EPUB’s consistent use of XML, when you use HTML5 in an EPUB, it needs to follow XML rules. They aren’t difficult; it just means that:

• you can’t omit end tags, as you can in HTML;
• element and attribute names are case-sensitive and need to be lowercase;
• you have to include the slash in empty tags like
  , and use “&” for ampersands in text;
• and you have to declare namespaces, which provide a way to specify a source of formal definitions of terms, along with prefixes that are then added to those terms to indicate that they are being used according to that specification.

Otherwise, the markup is HTML5. That’s what’s meant by “XHTML5.”

EPUB 3 takes the semantics a step further. While it is based on the semantics inherent in HTML5, it adds a new “Structural Semantics Vocabulary” and a new “epub:type” attribute that provide much more specific (and useful!) ways to characterize what the components are. For example, an