description: null package_name: fhir.nhs.uk.wayfinder derivation: constraint name: ExtensionWayfinderReadReceipt type: Extension elements: url: pattern: {type: uri, value: 'https://fhir.nhs.uk/StructureDefinition/Extension-Read-Receipt'} type: uri index: 0 value: short: read | unread | seen choices: [valueCode] index: 2 valueCode: {type: code, short: read | unread | seen, choiceOf: value, index: 3} package_version: 1.0.2 class: extension kind: complex-type url: https://fhir.nhs.uk/StructureDefinition/Extension-Read-Receipt base: http://hl7.org/fhir/StructureDefinition/Extension version: null required: [value, valueCode]