Medication representing a physical item of the same product – identifier is the stock-system number of the record; instance.identifier is the serial number and instance.lotNumber the batch (id = "med0325")

<?xml version="1.0" encoding="UTF-8"?>

<Medication xmlns="http://hl7.org/fhir">
  <id value="med0325"/> 
  <!--  A Medication representing a physical item (one pack on a pharmacy shelf) of the
   same product as medicationexample0324.
       identifier is the business identifier of this record (a stock-system number);
   instance.identifier is the serial number
       of the item; the batch is in instance.lotNumber, not in an identifier.  -->
  <identifier> 
    <system value="http://example.org/pharmacy-stock"/> 
    <value value="STK-2026-004711"/> 
  </identifier> 
  <code> 
    <coding> 
      <system value="http://www.nlm.nih.gov/research/umls/rxnorm"/> 
      <code value="308191"/> 
      <display value="amoxicillin 500 MG Oral Capsule"/> 
    </coding> 
  </code> 
  <status value="active"/> 
  <instance> 
    <identifier> 
      <system value="http://example.org/serial-number"/> 
      <value value="SN-48211907"/> 
    </identifier> 
    <lotNumber value="AX2604B"/> 
    <expirationDate value="2028-03-31"/> 
  </instance> 
</Medication>