f:Extension id: minimum cardinality of 'id' is 1 valueReference: minimum cardinality of 'valueReference' is 1 Extension All FHIR elements must have a @value or children Must have either extensions or value[x], not both Extension.id All FHIR elements must have a @value or children Extension.extension All FHIR elements must have a @value or children Must have either extensions or value[x], not both Extension.url All FHIR elements must have a @value or children f:Extension/f:valueReference id: maximum cardinality of 'id' is 0 reference: minimum cardinality of 'reference' is 1 identifier: maximum cardinality of 'identifier' is 0 display: maximum cardinality of 'display' is 0 Extension.valueReference All FHIR elements must have a @value or children Extension.valueReference.id All FHIR elements must have a @value or children Extension.valueReference.extension All FHIR elements must have a @value or children Must have either extensions or value[x], not both Extension.valueReference.reference All FHIR elements must have a @value or children Extension.valueReference.identifier All FHIR elements must have a @value or children Extension.valueReference.display All FHIR elements must have a @value or children