description: '**This extension is only used in the US Core Implementation Guide''''s Profile StructureDefinition elements.** It flags elements that are *Additional* USCDI Requirements for certified systems. In other words, elements that are not marked as Must Support but are required for ONC Health IT certification testing. See the [Conformance page](http://hl7.org/fhir/us/core/general-requirements.html) for more information.' package_name: hl7.fhir.us.core derivation: constraint name: USCDIRequirement type: Extension elements: url: pattern: {type: Uri, value: 'http://hl7.org/fhir/us/core/StructureDefinition/uscdi-requirement'} index: 0 value: choices: [valueBoolean] index: 2 valueBoolean: {type: boolean, choiceOf: value, index: 3} package_version: 7.0.0-ballot class: extension kind: complex-type url: http://hl7.org/fhir/us/core/StructureDefinition/uscdi-requirement base: http://hl7.org/fhir/StructureDefinition/Extension version: 7.0.0-ballot required: [value, valueBoolean]