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

  <!-- Example: Polyethylene Glycol 3350 (PEG 3350) — a homopolymer of ethylene
     oxide with number-average molecular weight ~3350 Da. Demonstrates the new
     SubstanceDefinition polymer backbones added for FHIR-57660: .polymer.class,
     .geometry, .monomerSet.startingMaterial, .repeat.repeatUnit with degree
     of polymerisation. Adapted from ISO 11238 Implementation Guide polymer
     example for PEG 3350. -->
<SubstanceDefinition xmlns="http://hl7.org/fhir">
  <id value="peg3350"/>
  <identifier>
    <system value="http://example.europa.eu/fhir/SMSId"/>
    <value value="PEG3350P"/>
  </identifier>
  <status>
    <coding>
      <system value="http://hl7.org/fhir/publication-status"/>
      <code value="active"/>
      <display value="Active"/>
    </coding>
  </status>
  <classification>
    <coding>
      <system value="http://example.europa.eu/fhir/SubstanceType"/>
      <code value="polymer"/>
      <display value="Polymer"/>
    </coding>
  </classification>
  <domain>
    <coding>
      <system value="http://example.europa.eu/fhir/Domain"/>
      <code value="human"/>
      <display value="Human use"/>
    </coding>
  </domain>
  <description value="Polyethylene Glycol 3350 (PEG 3350, Macrogol 3350) — a synthetic polyether of ethylene oxide with number-average molecular weight approximately 3350 Da. Linear homopolymer used as an osmotic laxative and a pharmaceutical excipient."/>
  <code>
    <code>
      <coding>
        <system value="http://example.europa.eu/fhir/Substance"/>
        <code value="PEG3350P"/>
      </coding>
    </code>
  </code>
  <name>
    <name value="Polyethylene Glycol 3350"/>
    <preferred value="true"/>
    <language>
      <coding>
        <system value="urn:ietf:bcp:47"/>
        <code value="en"/>
        <display value="English"/>
      </coding>
    </language>
    <official>
      <authority>
        <coding>
          <system value="http://hl7.org/fhir/substance-name-authority"/>
          <code value="USAN"/>
          <display value="USAN"/>
        </coding>
      </authority>
      <status>
        <coding>
          <system value="http://hl7.org/fhir/publication-status"/>
          <code value="active"/>
          <display value="Active"/>
        </coding>
      </status>
    </official>
  </name>
  <name>
    <name value="Macrogol 3350"/>
    <preferred value="false"/>
  </name>
  <molecularWeight>
    <type>
      <coding>
        <system value="http://example.europa.eu/fhir/WeightType"/>
        <code value="number-average"/>
        <display value="Number average (Mn)"/>
      </coding>
    </type>
    <amount>
      <value value="3350"/>
      <unit value="g/mol"/>
      <system value="http://unitsofmeasure.org"/>
      <code value="g/mol"/>
    </amount>
  </molecularWeight>
  <polymer>
    <class>
      <coding>
        <system value="http://hl7.org/fhir/polymer-class"/>
        <code value="homopolymer"/>
        <display value="Homopolymer"/>
      </coding>
    </class>
    <geometry>
      <coding>
        <system value="http://hl7.org/fhir/polymer-geometry"/>
        <code value="linear"/>
        <display value="Linear"/>
      </coding>
    </geometry>
    <monomerSet>
      <ratioType>
        <coding>
          <system value="http://hl7.org/fhir/polymer-monomer-ratio-type"/>
          <code value="monomer-polymer-ratio"/>
          <display value="Monomer/Polymer ratio"/>
        </coding>
      </ratioType>
      <startingMaterial>
        <code>
          <concept>
            <coding>
              <system value="http://example.europa.eu/fhir/Substance"/>
              <code value="ethylene-oxide"/>
              <display value="Ethylene oxide"/>
            </coding>
          </concept>
        </code>
        <category>
          <coding>
            <system value="http://hl7.org/fhir/polymer-starting-material-category"/>
            <code value="chemical-substance"/>
            <display value="Chemical substance"/>
          </coding>
        </category>
        <isDefining value="true"/>
        <amount>
          <value value="76"/>
          <unit value="monomers per polymer"/>
        </amount>
      </startingMaterial>
    </monomerSet>
    <repeat>
      <averageMolecularFormula value="(C2H4O)76"/>
      <repeatUnitAmountType>
        <coding>
          <system value="http://hl7.org/fhir/polymer-monomer-ratio-type"/>
          <code value="sru-polymer-ratio"/>
          <display value="SRU/Polymer ratio"/>
        </coding>
      </repeatUnitAmountType>
      <repeatUnit>
        <unit value="-CH2-CH2-O-"/>
        <orientation>
          <coding>
            <system value="http://hl7.org/fhir/polymerisation-orientation"/>
            <code value="head-tail"/>
            <display value="Head-to-tail"/>
          </coding>
        </orientation>
        <amount value="76"/>
        <degreeOfPolymerisation>
          <type>
            <coding>
              <system value="http://hl7.org/fhir/degree-of-polymerisation-type"/>
              <code value="number-average"/>
              <display value="Number average"/>
            </coding>
          </type>
          <average value="76"/>
          <low value="70"/>
          <high value="82"/>
        </degreeOfPolymerisation>
      </repeatUnit>
    </repeat>
  </polymer>
</SubstanceDefinition>