description: This extension is used by the provider to assign a unique identifier to this item. The intent of this element is to allow the provider to assign something other than 'line number' for their purposes (e.g. tracking and troubleshooting). package_name: hl7.fhir.us.davinci-pct derivation: constraint name: GFEBillingProviderLineItemCtrlNum type: Extension elements: extension: {index: 0} url: pattern: {type: Uri, value: 'http://hl7.org/fhir/us/davinci-pct/StructureDefinition/gfeBillingProviderLineItemCtrlNum'} index: 1 value: choices: [valueIdentifier] index: 3 valueIdentifier: {type: Identifier, choiceOf: value, index: 4} package_version: 2.0.0-ballot extensions: {} class: extension kind: complex-type url: http://hl7.org/fhir/us/davinci-pct/StructureDefinition/gfeBillingProviderLineItemCtrlNum base: http://hl7.org/fhir/StructureDefinition/Extension version: 2.0.0-ballot required: [valueIdentifier, value]