ef="https://w3c.github.io/epub-specs/epub33/core/"><em>editors’ draft</em></a> of the specification.
                        </p>
                            
                    </li>
                    <li id="exit-criteria-core-4">
                        <p>
                          Testing the features in category 4 concentrates on vocabulary term <em>usage</em>, i.e., whether real-world publishers use those terms. Each term must have at least two independent publishers using those terms in product