The Service Event provides information on the service that is the subject of the document.
Depending on the document type, an instance may contain documentation of a specific
service event and the related performers (for instance, a Procedure Note would document
the specific procedure event). If a Service Event is included in the document, it
must be equivalent to, or further specialize, the value inherent in the Document Type;
it shall not conflict with the document type as such a conflict would constitute an
ambiguous situation.