An "ask at order" response using the datetime datetype for the result value (id = "date-lastmp")

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

<Observation xmlns="http://hl7.org/fhir">
  <id value="date-lastmp"/> 
  <status value="final"/> 
  <category> 
    <coding> 
      <system value="http://terminology.hl7.org/CodeSystem/observation-category"/> 
      <code value="survey"/> 
      <display value="Survey"/> 
    </coding> 
    <text value="AOE"/> 
  </category> 
  <code> 
    <coding> 
      <system value="http://loinc.org"/> 
      <code value="8665-2"/> 
      <display value="Last menstrual period start date"/> 
    </coding> 
    <text value="Last menstrual period start date"/> 
  </code> 
  <subject> 
    <reference value="Patient/pat2"/> 
  </subject> 
  <effectiveDateTime value="2016-01-24"/> 
  <valueDateTime value="2016-12-30"/> 
</Observation>