Implementers will commonly need to define requests for several medications in one "order".

These may be processed separately, or they may belong together, as the act of prescribing entails a clinical responsibility for a given set of medications, and any change to that set's integrity has potential clinical impact.

In several (most?) countries in EU, the prescription contains one or several "items" or "lines". See for example

http://www.ihe.net/uploadedFiles/Documents/Pharmacy/IHE_Pharmacy_Suppl_PRE.pdf?#page=12

The MedicationRequest resource corresponds to one medication line. What is the equivalent to a "prescription" in this vocabulary?

Can we provide guidance on how to make a simple/common prescription with several items?

Example: an antiemetic or PPI to minimize discomfort and protect the patient from other medications - in which case, none of the drugs should be considered in isolation and the clinician is responsible for the integrity of the treatment.

This is a request to disambiguate concepts, not to force a definition of "prescription" (which is usually defined already in legal frameworks).