Working Group Note: EPUB 3 Structural Semantics Vocabulary 1.1

November 4th, 2021

The EPUB 3 Working Group has just published the Working Group Note of EPUB 3 Structural Semantics Vocabulary 1.1. This vocabulary, a part of EPUB 3, defines a set of properties relating to the description of structural semantics of written works.

Structural semantics add additional meaning about the specific structural purpose an HTML (or SVG) element plays. The epub:type attribute, defined in EPUB 3.3, is used to express domain-specific semantics in EPUB Content Documents and Media Overlay Documents, with the structural information it carries complementing the underlying vocabulary. The applied semantics refine the meaning of their containing elements without changing their nature for assistive technologies, as happens when using the similar role attribute in HTML. The attribute does not enhance the accessibility of the content, in other words, only provides hints about the purpose. This documents defines the default vocabulary that can be used with the epub:type attribute.