Content model for the <book-part-wrapper> element
<!ENTITY % book-part-wrapper-model
"(collection-meta*, book-meta,
(%book-parts-mix;) )" >(collection-meta*, book-meta, (book-part | xi:include | app | app-group | floats-group | index | index-group | ref-list | front-matter-part | foreword | preface | notes | ack | bio | dedication | fn-group | glossary | toc | toc-group) )