def handle_observation_criteria
      exp = @entry.at_xpath('./cda:measureObservationDefinition/cda:value/cda:expression/@value',
                            HQMF2::Document::NAMESPACES)
      # Measure Observations criteria rely on computed expressions. If it doesn't have one,
      #  then it is likely formatted improperly.
      fail 'Measure Observations criteria is missing computed expression(s) ' if exp.nil?
      parts = exp.to_s.split('-')
      dc = parse_parts_to_dc(parts)
      @doc.add_data_criteria(dc)
      # Update reference_ids with any newly referenced data criteria
      dc.children_criteria.each { |cc| @doc.add_reference_id(cc) } unless dc.children_criteria.nil?
      dc
    end
def handle_observation_criteria
      exp = @entry.at_xpath('./cda:measureObservationDefinition/cda:value/cda:expression/@value',
                            HQMF2::Document::NAMESPACES)
      # Measure Observations criteria rely on computed expressions. If it doesn't have one,
      #  then it is likely formatted improperly.
      fail 'Measure Observations criteria is missing computed expression(s) ' if exp.nil?
      parts = exp.to_s.split('-')
      dc = parse_parts_to_dc(parts)
      @doc.add_data_criteria(dc)
      # Update reference_ids with any newly referenced data criteria
      dc.children_criteria.each { |cc| @doc.add_reference_id(cc) } unless dc.children_criteria.nil?
      dc
    end
extracts out any measure observation definitons, creating from them the proper criteria to generate a precondition