The schema has expunged all references to "chapter" and "subsection" elements. They're all now sections: either the tradition "cc:section" element or the new form described below.

An xml document with a singled, deeply nested element quickly can become unreadable by humans and difficult to manage. The following is valid, but (a little) discouraged:

<section title="abc" id="abc">
   <section title="def" id="anId">
     <section title="with space">
       ...
     </section>
   </section>
 </section>

The following is functionally equivalent to the snippet above, but more readable.

<cc:PP xmlns:sec="https://niap-ccevs.org/cc/v1/section"...>
...
<sec:abc>
   <sec:anId title="def">
     <sec:with_space> The title of this section is "with space"
       ...
     </sec:with_space>
   </sec:anId>
</sec:abc>

In this form, the ID of the section is the local-name of the element (i.e. the part following the colon). The title of the section, if not explicitly assigned with a title attribute, is derived from the ID, by replacing every underscore with space.

All specific cross-reference elements--fig-ref, secref, ctr-ref, appref, etc-- have been converted to the generic xref. Similiarly the linkref attribute was converted to the to attribute or the g attribute. The to attribute references things in the PP that have an id attribute in the XML form. The g attribute references items that are dynamically generated by the framework. The schema should help you out with what's allowable, but it doesn't list everything currently. Let us know if we overlooked a value.