description: Sort key values allow laboratories to suggest the sequence of test requests and observations within a single order or test request to organize the display of the patient report by other external systems (e.g., a practitioner’s electronic medical record system). package_name: ca.on.ehr.r4 derivation: constraint name: SortKey type: Extension elements: url: pattern: {type: Uri, value: 'http://ehealthontario.ca/fhir/StructureDefinition/ca-on-lab-ext-sort-key'} index: 0 value: choices: [valueString] index: 2 valueString: {type: string, choiceOf: value, index: 3} package_version: 1.0.0-snapshot4 class: extension kind: complex-type url: http://ehealthontario.ca/fhir/StructureDefinition/ca-on-lab-ext-sort-key base: http://hl7.org/fhir/StructureDefinition/Extension version: null