Comment:

class cardinality should be 1..1 as mentioned in section 8.11.4 Notes

The class element describes the setting (in/outpatient etc.) in which the Encounter took place. Since this is important for interpreting the context of the encounter, choosing the appropriate business rules to enforce and for the management of the process, this element is required. Moreover in class history it is marked as 1..1, so unless it is mandatory in current encounter, there won't be way to have it mandated in history

Summary:

Encounter.class should be 1..1