description: To be used when the actual gateway used at the time of the observation, and the referenced device is also specified. The gateway device may be acting as a communication/data collector, translator or controller; This extension is useful when there is more than one gateway device, for example, where there are apps on a phone and each are a device, and more than one app is used to pass on the data to a FHIR Server. In that case you need to be able to say from the observation which specific app was used to act as gateway. Note that the Provenance/AuditEvent resources can represent the same information. package_name: hl7.fhir.uv.extensions derivation: constraint name: ObsGatewayDevice type: Extension elements: extension: {index: 0} url: pattern: {type: Uri, value: 'http://hl7.org/fhir/StructureDefinition/observation-gatewayDevice'} index: 1 value: choices: [valueReference] index: 3 valueReference: type: Reference choiceOf: value refers: ['http://hl7.org/fhir/StructureDefinition/Device'] index: 4 package_version: 5.1.0-snapshot1 extensions: {} class: extension kind: complex-type url: http://hl7.org/fhir/StructureDefinition/observation-gatewayDevice base: http://hl7.org/fhir/StructureDefinition/Extension version: 5.1.0-snapshot1 required: [valueReference, value]