Metadata for Series
If the title passport contains the Series then add this value to a metaDescribes element with predicate="series".
Example
<book doi="10.1093/med/9780199606481.001.0001" id="med-9780199606481">
<bookMeta><metaItem about="book">
<!-- [other metaDescribes elements] -->
<metaDescribes predicate="series">Oxford Medical Handbooks</metaDescribes></metaItem>
</bookMeta>
</book>