http://hl7.org/fhir/StructureDefinition/humanname-partner-name|5.2.0

The portion of the family name that is derived from the person's partner's surname, as distinguished from any portion that is derived from the surname of the person's own name.
typedestination
baseDefinitionhttp://hl7.org/fhir/StructureDefinition/Extension
typehttp://hl7.org/fhir/StructureDefinition/Extension
Extension.value[x].typehttp://hl7.org/fhir/StructureDefinition/string