The documentation for type says:

Specifies the particular kind of document.

Whereas class says:

A categorization for the type of document.

One of these fields has example values of "Patient Summary" and "Prescription", whereas the other has example values of "Patient Preferences" and "Summary". I don't know what principles a reader is supposed to discern from reading these descriptions and examples; the distinction is unclear.

If possible these fields should be collapsed. If they are both needed, then further work is required to clarify why.