XMI24 — Section 5.2.2:

Section 5.2.2: The elements for documentation must be included within in the “XMI” complexType; Also XMIPackage should be removed as a consequence of Issue 9694. More generally section 5.2.2 duplicates both 4.5.3 (which has the schema presented section by section) and the separate machine readable CMI.xsd file and hence introduces lots of room for error – so should be removed

Delete the Schema part of 5.2.2.
The documentation elements cannot be included in the complex type for XMI since they would violate the ‘unique particle attribution rule’ since the XMI element also has a xsd:any element. However there is confusion cause by the existence of doth these elements and the elements with upper case: which are only valid if used as top level elements.