description: A short mnemonic code - historically a three letter acronym (TLA) - for a resource type. It is used as a compact abbreviation for the resource, for example when constructing identifiers or short cross-references. The code is not required to be exactly three characters. package_name: hl7.fhir.uv.tools derivation: constraint name: ResourceTLA type: Extension elements: extension: {index: 0} url: pattern: {type: Uri, value: 'http://hl7.org/fhir/tools/StructureDefinition/resource-tla'} index: 1 value: choices: [valueString] index: 3 valueString: {type: string, choiceOf: value, index: 4} package_version: 1.2.0 extensions: {} class: extension kind: complex-type url: http://hl7.org/fhir/tools/StructureDefinition/resource-tla base: http://hl7.org/fhir/StructureDefinition/Extension version: 1.2.0 required: [valueString, value]