I wonder if it makes sense to align subelements of ContentType, ClassificationEntry and Annotation?

In the STC namespace the complexType of ContentType and ClassificationEntry allows mixed content (text AND other sub elements), whereas in the SSC namespace this is not the case for Annotation, which leads to the result that XML-subelements MUST be defined in the Annotation element. Imho this brings in unnecessary complexity for Annotation...

See the comparison

<ssc:Annotation type="...">
    <unnecessarySubelement> arbitrary annotation </unnecessarySubelement>
</ssc:Annotation>

<stc:Content> arbitrary content </stc:Content>