<status value="active" /> <fhirVersion value="4.0.1" /> <kind value="complex-type" /> <abstract value="false" /> <context> <type value="element" /> <expression value="SubstanceSpecification" /> </context> <type value="Extension" /> <baseDefinition value="http://hl7.org/fhir/StructureDefinition/Extension" /> <derivation value="constraint" /> <differential> <element id="Extension"> <path value="Extension" /> <short value="GSRS Substance ID" /> <definition value="The Unique Ingredient Identifier (UNII) generated by the [Global Substance Registration System (GSRS)](https://gsrs.ncats.nih.gov/) of the US Food and Drug Administration. System URL: [https://mpd.noma.no/identifier/unii-code](https://mpd.noma.no/identifier/unii-code)" /> <max value="1" /> </element> <element id="Extension.id"> <path value="Extension.id" /> <max value="0" /> </element> <element id="Extension.extension"> <path value="Extension.extension" /> <max value="0" /> </element> <element id="Extension.url"> <path value="Extension.url" /> <fixedUri value="https://mpd.noma.no/identifier/unii-code" /> </element> <element id="Extension.value[x]"> <path value="Extension.value[x]" /> <type> <code value="Identifier" /> </type> </element> <element id="Extension.value[x].id"> <path value="Extension.value[x].id" /> <max value="0" /> </element> <element id="Extension.value[x].use"> <path value="Extension.value[x].use" /> <max value="0" /> </element> <element id="Extension.value[x].type"> <path value="Extension.value[x].type" /> <max value="0" /> </element> <element id="Extension.value[x].system"> <path value="Extension.value[x].system" /> <min value="1" /> </element> <element id="Extension.value[x].value"> <path value="Extension.value[x].value" /> <min value="1" /> </element> <element id="Extension.value[x].assigner"> <path value="Extension.value[x].assigner" /> <max value="0" /> </element> </differential> </StructureDefinition>