The scope of the MedicationPrescription goes well beyond prescriptions and medication orders. It also encompasses the following things:

• encoded orders created by the pharmacy based on a prescription/med order
  - MAR entries within a nursing system
  - recommendations provided from a decision support engine that a patient be on a particular medication
  - a care plan that includes a plan for a patient to be on a particular medication

These additional uses aren't terribly clear from the existing name. As well, some of the descriptions seem to limit themselves to the "order" use-case. Consider renaming to MedicationRequest with an alias of Prescription and ensure descriptions are clear