description: This is the first date-time when the value set version becomes active, so this value is present on Inactive value set versions as well. The start Date_time is expected to be as of 0001 UTC of the Effective Date. package_name: hl7.fhir.uv.extensions derivation: constraint name: CodeSystemEffectiveDate type: Extension elements: extension: {index: 0} url: pattern: {type: uri, value: 'http://hl7.org/fhir/StructureDefinition/codesystem-effectiveDate'} type: uri index: 1 value: choices: [valueDate] index: 3 valueDate: {type: date, choiceOf: value, index: 4} package_version: 5.3.0-ballot-tc extensions: {} class: extension kind: complex-type url: http://hl7.org/fhir/StructureDefinition/codesystem-effectiveDate base: http://hl7.org/fhir/StructureDefinition/Extension version: 5.3.0-ballot-tc required: [value, valueDate]